Vanguard Variable Insurance Funds (the “Trust”)

Supplement Dated June 29, 2026, to the Statement of Additional Information Dated April 28, 2026

Important Changes to Vanguard Variable Insurance Funds – Small Company Growth Portfolio

Restructuring of the Investment Advisory Team

A majority of the independent trustees of Vanguard Variable Insurance Funds, on behalf of Vanguard Variable Insurance Funds – Small Company Growth Portfolio (the “Fund”), has approved a restructuring of the Fund’s investment advisory team, removing ArrowMark Colorado Holdings, LLC (“ArrowMark Partners”) as an investment advisor to the Fund and adding T. Rowe Price Associates, Inc. (“T. Rowe Price”). The Vanguard Group, Inc. (“Vanguard”) through its wholly owned subsidiary, Vanguard Portfolio Management (“VPM”) remains an advisor to the Fund.

The Fund operates under the terms of an SEC exemption, whereby the Fund’s Board of Trustees may, without prior approval from shareholders, hire new advisors.

Effective immediately, T. Rowe Price manages a portion of the Fund’s assets along with the Fund’s existing advisor Vanguard. Each advisor independently manages its assigned portion of the Fund’s assets, subject to the supervision and oversight of Vanguard and the Board. The Fund’s Board of Trustees determines the proportion of the Fund’s assets to be managed by each advisor and may change these proportions at any time.

In connection with the addition of T. Rowe Price to the Fund, David Corris and Prashant Jeyaganesh are added as co-portfolio managers of the T. Rowe Price portion of the Fund.

The restructuring of the Fund’s investment advisory arrangements is expected to increase the Fund’s expense ratio by three basis points, from 29 to 32 basis points.

The Fund’s investment objective, principal investment strategies, and policies remain unchanged.

Statement of Additional Information Text Changes

All references to ArrowMark Partners and all other details and descriptions regarding ArrowMark Partners’ management of certain assets of the Fund in the Statement of Additional Information are deleted in their entirety.

In the Investment Advisory and Other Services section, the following is added to the list of investment advisors:

■T. Rowe Price Associates, Inc. (T. Rowe Price) provides investment advisory services for a portion of Small Company Growth Portfolio.

ArrowMark Partners provided investment advisory services to the Fund from 2016 until June 2026.

Within the same section, the following replaces in its entirety similar text under V. Small Company Growth Portfolio on page B-81:

The Fund pays T. Rowe Price a base fee plus or minus a performance adjustment. The base fee, which is paid quarterly, is a percentage of average daily net assets managed by the advisor during the most recent fiscal quarter. The performance adjustment, also paid quarterly, is based on the cumulative total return of the advisor’s portion of the Fund relative to that of the Russell 2500 Growth Index over the preceding 36-month period.

Within the same section, the following is added as a new sub-section beginning on page B-81:

A. T. Rowe Price Associates, Inc. (T. Rowe Price)

T. Rowe Price Associates, Inc., 1307 Point Street, Baltimore, Maryland 21231, is a wholly owned subsidiary of T. Rowe

Price Group, Inc. and was founded in 1937. As of March 31, 2026, T. Rowe Price and its affiliates managed approximately $1.78 trillion in assets under management.

1. Other Accounts Managed

The following table provides information relating to the other accounts managed by the portfolio managers of the Fund as of April 30, 2026 (unless otherwise noted):

1 The data in the table does not include Vanguard Explorer Fund, which Mr. Corris and Mr. Jeyaganesh manage as of June 29, 2026.

2. Material Conflicts of Interest

Portfolio managers at T. Rowe Price and its affiliates may manage multiple accounts. These accounts may include, among others, mutual funds, exchange-traded funds, business development companies, separate accounts (assets managed on behalf of institutions such as pension funds, colleges and universities, and foundations), offshore funds, private funds, and common trust funds. T. Rowe Price also provides nondiscretionary advice to institutional investors in the form of delivery of model portfolios. Like other investment professionals with multiple clients, a fund’s portfolio manager(s) may face certain potential conflicts of interest in connection with managing both a fund and other accounts at the same time. T. Rowe Price and the T. Rowe Price funds have adopted various compliance policies and procedures that seek to address and mitigate certain of the potential conflicts that T. Rowe Price and its investment personnel may face in this regard.

Portfolio managers make investment decisions for each portfolio based on the investment objectives, policies, practices, and other relevant investment considerations that they believe are applicable to that portfolio. Consequently, portfolio managers may purchase (or sell) securities for one portfolio and not another portfolio. Investments made by a fund and the results achieved by a fund at any given time are not expected to be the same as those made by other funds for which T. Rowe Price acts as investment advisor, including funds with names, investment objectives and policies, and/or portfolio management teams, similar to a fund. This may be attributable to a wide variety of factors, including, but not limited to, large shareholder purchases or redemptions or specific investment restrictions.

The T. Rowe Price funds generally may not purchase shares of stock issued by T. Rowe Price Group, Inc. However, a T. Rowe Price Index Fund is permitted to make such purchases to the extent T. Rowe Price Group, Inc., is represented in the benchmark index the fund is designed to track. T. Rowe Price may execute securities transactions with, and the T. Rowe Price funds and other accounts managed by T. Rowe Price may invest in, the securities of the fund’s service providers. In addition, other T. Rowe Price accounts may use the same service providers as the T. Rowe Price funds for the same or different services.

T. Rowe Price and its affiliates furnish investment management and advisory services to numerous clients in addition to the T. Rowe Price funds, and T. Rowe Price or its affiliates may, consistent with applicable law, make investment recommendations to other clients or accounts (including accounts that have performance or higher fees paid to T. Rowe Price), which may be the same as or different from those made to a T. Rowe Price fund. The management of funds or other accounts with different advisory fee rates and/or fee structures, including accounts that pay advisory fees based on account performance (performance fee accounts), may raise potential conflicts of interest by creating an incentive to favor accounts that pay higher fees, including performance fee accounts.

The same portfolio manager(s) could serve as portfolio manager to one or more Price mutual funds or ETFs. That portfolio manager may determine to have one Price mutual fund or ETF (Investing Fund) invest in another Price mutual fund or ETF (Underlying Fund) and may have incentives, such as to support an investment strategy or cash flow needs.

Moreover, a situation could occur where the best interests of the Investing Fund could be adverse to the best interests of an Underlying Fund or vice versa. For example, conflicts could arise in voting proxies or purchasing or redeeming shares of the Underlying Fund in a manner beneficial to the Investing Fund but potentially detrimental to the Underlying Fund (or vice versa). The T. Rowe Price funds may be either an Investing Fund or Underlying Fund.

T. Rowe Price and the portfolio managers have a fiduciary duty to act in the best interests of each T. Rowe Price fund. Under the oversight of the Board and pursuant to applicable policies and procedures, T. Rowe Price will carefully analyze any such situation and take all steps it believes necessary to minimize and, where possible, eliminate potential conflicts. The Investing Fund’s or Underlying Fund’s activities may be limited or restricted because of laws and regulations applicable to T. Rowe Price, the T. Rowe Price fund, or applicable policies and procedures. For example, if a portfolio manager comes into possession of material, non-public information about an Investing Fund or Underlying Fund, the portfolio manager could potentially be restricted from transacting in either fund, which may adversely affect the T. Rowe Price fund. T. Rowe Price, its affiliates, and significant shareholders and any officer, director, shareholder, or employee may or may not have an interest in the securities whose purchase and sale T. Rowe Price recommends to the T. Rowe Price funds. In certain circumstances, a T. Rowe Price employee, officer, or director may serve on the board of a T. Rowe Price fund’s portfolio company. In addition, T. Rowe Price may refrain from rendering any advice or services concerning securities of companies of which any of T. Rowe Price’s (or its affiliates’ or significant shareholders’) officers, directors, or employees are directors or officers, or companies in which T. Rowe Price or any of its affiliates or significant shareholders or the officers, directors, and employees of any of them has any substantial interest or possesses material nonpublic information.

Additional potential conflicts may be inherent in our use of multiple strategies. For example, conflicts will arise in cases where different clients invest in different parts of an issuer’s capital structure, including circumstances in which one or more clients may own private securities or obligations of an issuer and other clients may own or seek to acquire securities of the same issuer. For example, a client may acquire a loan, loan participation, or loan assignment of a particular borrower in which one or more other clients have an equity investment or may invest in senior debt obligations of an issuer for one client and junior debt obligations or equity of the same issuer for another client. Similarly, if an issuer in which a client and one or more other clients directly or indirectly hold different classes of securities (or other assets, instruments, or obligations issued by such issuer or underlying investments of such issuer) encounters financial problems, is involved in a merger or acquisition or a going private transaction, decisions over the terms of any workout or transaction will raise conflicts of interests. While it is appropriate for different clients to hold investments in different parts of the same issuer’s capital structure under normal circumstances, the interests of stockholders and debt holders may conflict, as the securities they hold will likely have different voting rights, dividend or repayment priorities, or other features that could be in conflict with one another. Clients should be aware that conflicts will not necessarily be resolved in favor of their interests.

In some cases, T. Rowe Price or its affiliates may refrain from taking certain actions or making certain investments on behalf of clients in order to avoid or to mitigate certain conflicts of interest or to prevent adverse regulatory actions or other implications for T. Rowe Price or its affiliates or may sell investments for certain clients, in such case potentially disadvantaging the clients on whose behalf the actions are not taken, investments not made, or investments sold. In other cases, T. Rowe Price or its affiliates may take actions in order to mitigate legal risks to T. Rowe Price or its affiliates, even if disadvantageous to a client.

Conflicts such as those described above may also occur between clients, on the one hand, and T. Rowe Price or its affiliates, on the other. These conflicts will not always be resolved in the favor of the client. In addition, conflicts may exist between different clients of T. Rowe Price or its affiliates. T. Rowe Price and one or more of its affiliates may operate autonomously from each other and may take actions that are adverse to other clients managed by an affiliate. In some cases, T. Rowe Price or its affiliates will have limited or no ability to mitigate those actions or address those conflicts, which could adversely affect T. Rowe Price or its affiliates’ clients. Additional potential conflicts may be inherent in T. Rowe Price’s use of multiple strategies. Regulatory requirements may prohibit T. Rowe Price or its affiliates from investing in certain companies on behalf of some of their clients, including the T. Rowe Price funds, while at the same time not prohibiting T. Rowe Price or its affiliates from making those same investments on behalf of other clients that are not subject to such requirements. T. Rowe Price’s or its affiliates’ ability to negotiate certain rights or remedies or to take other actions on behalf of the T. Rowe Price funds with respect to an investment also may be limited in situations in which an affiliate of the T. Rowe Price funds (or certain other interested persons) have a direct or indirect interest in the same issuer. When permitted by applicable law, other clients of T. Rowe Price or its affiliates, on the one hand, and one or more T. Rowe Price funds, on the other hand, may invest in or extend credit to different classes of securities or different parts of the capital structure of a single issuer. T. Rowe Price or its affiliates may pursue rights; provide advice or engage in other activities; or refrain from pursuing rights, providing advice, or engaging in other

activities, on behalf of themselves or one or more clients other than the T. Rowe Price funds with respect to an issuer in which a T. Rowe Price fund has invested, and such actions (or refraining from action) may have a material adverse effect on such T. Rowe Price fund. In addition, as a result of regulatory requirements or otherwise, in situations in which T. Rowe Price clients hold positions in multiple parts of the capital structure of an issuer, T. Rowe Price or its affiliates may not pursue certain actions that may otherwise be available. T. Rowe Price and its affiliates address these and other potential conflicts of interest based on the facts and circumstances of particular situations. For example, T. Rowe Price may determine to rely on one or more information barriers between different advisors, business units, or portfolio management teams or to rely on the actions of similarly situated holders of loans or securities rather than, or in connection with, taking such actions itself on behalf of a client. In these situations, investment personnel are mindful of potentially conflicting interests of our clients with investments in different parts of an issuer’s capital structure and seek to take appropriate measures to ensure that the interests of all clients are fairly represented. As a result of the various conflicts and related issues described in this paragraph, a T. Rowe Price fund could sustain losses during periods in which T. Rowe Price or its affiliates and other clients of T. Rowe Price or its affiliates achieve profits generally or with respect to particular holdings or could achieve lower profits or higher losses than would have been the case had the conflicts described above not existed.

3. Description of Compensation

The compensation structure for the T. Rowe Price funds’ portfolio managers consists primarily of a base salary, a cash bonus, and an equity incentive that usually comes in the form of restricted stock grants. Compensation is variable and is determined based on the following factors.

Investment performance over 1-, 3-, 5-, and 10-year periods is the most important input. The weightings for these time periods are generally balanced and are applied consistently across similar strategies. T. Rowe Price (and T. Rowe Price Australia, T. Rowe Price Hong Kong, T. Rowe Price Singapore, T. Rowe Price Japan, T. Rowe Price International, and T. Rowe Price Investment Management, as appropriate) evaluates performance in absolute, relative, and risk-adjusted terms. Relative performance and risk-adjusted performance are typically determined with reference to the broad-based index (e.g., S&P 500 Index) and the Lipper average or index (e.g., Large-Cap Growth Index) set forth in the total returns table in the fund’s prospectus, although other benchmarks may be used as well. Investment results are also measured against comparably managed funds of competitive investment management firms. The selection of comparable funds is approved by the applicable investment steering committee and is the same as the selection presented to the directors of the T. Rowe Price funds in their regular review of fund performance. Performance is primarily measured on a pretax basis, although tax efficiency is considered.

Compensation is viewed with a long-term time horizon. The more consistent a portfolio manager’s performance over time, the higher the compensation opportunity. The increase or decrease in a fund’s assets due to the purchase or sale of fund shares is not considered a material factor. In reviewing relative performance for fixed income funds, a fund’s expense ratio is usually taken into account. Contribution to T. Rowe Price’s overall investment process is an important consideration as well. Leveraging ideas and investment insights across applicable investment platforms; working effectively with and mentoring others; and other contributions to our clients, the firm, or our culture are important components of T. Rowe Price’s long-term success and are generally taken into consideration.

All employees of T. Rowe Price, including portfolio managers, can participate in a 401(k) plan sponsored by T. Rowe Price Group. In addition, all employees are eligible to purchase T. Rowe Price common stock through an employee stock purchase plan that features a limited corporate matching contribution. Eligibility for and participation in these plans is on the same basis for all employees. Finally, all vice presidents of T. Rowe Price Group, including all portfolio managers, are eligible to participate in a supplemental savings plan sponsored by T. Rowe Price Group, and certain vice presidents of T. Rowe Price Group receive supplemental medical/hospital reimbursement benefits.

This compensation structure is used when evaluating the performance of all portfolios managed by the portfolio manager.

4. Ownership of Securities

As of April 30, 2026, Mr. Corris and Mr. Jeyaganesh did not own any shares of the Fund.

The following is added to Appendix B of this Statement of Additional Information:

T. Rowe Price Associates, Inc. and Certain of Its Investment Advisor Affiliates

Governance Team. Our Governance team is responsible for reviewing the proxy agendas for all upcoming meetings and making company-specific recommendations to our global industry analysts and portfolio managers with regard to the voting decisions in their portfolios.

Responsible Investment Team. Our Responsible Investment team oversees the integration of environmental and social factors into our investment processes across asset classes. In formulating vote recommendations for matters of an environmental or social nature, the Governance team consults with the appropriate sector analyst from the Responsible Investment team, as appropriate.

HOW PROXIES ARE REVIEWED, PROCESSED AND VOTED

In order to facilitate the proxy voting process, T. Rowe Price has retained Institutional Shareholder Services (“ISS”) as an expert in the proxy voting and corporate governance area. ISS specializes in providing a variety of fiduciary-level proxy advisory and voting services. These services include custom vote recommendations, research, vote execution, and reporting. Services provided by ISS do not include automated processing of votes on our behalf using the ISS Benchmark Policy recommendations. Instead, in order to reflect T. Rowe Price’s issue-by-issue voting guidelines as approved each year by the TRPA ESG Investing Committee, ISS maintains and implements custom voting policies for the Price Funds and other advisory client accounts.

Meeting Notification

T. Rowe Price utilizes ISS’ voting agent services to notify us of upcoming shareholder meetings for portfolio companies held in client accounts and to transmit votes to the various custodian banks of our clients. ISS tracks and reconciles our clients’ holdings against incoming proxy ballots. If ballots do not arrive on time, ISS procures them from the appropriate custodian or proxy distribution agent. Meeting and record date information is updated daily and transmitted to T. Rowe Price through ProxyExchange, an ISS application.

Vote Determination

Each day, ISS delivers into T. Rowe Price’s customized ProxyExchange environment a comprehensive summary of upcoming meetings, proxy proposals, publications discussing key proxy voting issues, and custom vote recommendations to assist us with proxy research and processing. For meetings with complex ballot items in certain international markets, research may be consulted from local domestic proxy research providers. The final authority and responsibility for proxy voting decisions remains with T. Rowe Price. Decisions with respect to proxy matters are made primarily in light of the anticipated impact of the issue on the desirability of investing in the company from the perspective of our clients.

Portfolio managers execute their responsibility to vote proxies in different ways. Some have decided to vote their proxies generally in line with the guidelines as set by the TRPA ESG Investing Committee. Others review the customized vote recommendations and approve them before the votes are cast. Portfolio managers have access to current reports summarizing all proxy votes in their client accounts. Portfolio managers who vote their proxies inconsistent with T. Rowe Price guidelines are required to document the rationale for their votes. The Global Proxy Operations team is responsible for maintaining this documentation and assuring that it adequately reflects the basis for any vote which is contrary to our proxy voting guidelines.

T. Rowe Price Voting Guidelines

Specific proxy voting guidelines have been adopted by the TRPA ESG Investing Committee for all regularly occurring categories of management and shareholder proposals. The guidelines include regional voting guidelines as well as the guidelines for investment strategies with objectives other than purely financial returns, such as Impact and Net Zero. A detailed set of proxy voting guidelines is available on the T. Rowe Price website, www.troweprice.com/esg or click here.

Global Portfolio Companies

The TRPA ESG Investing Committee has developed custom international proxy voting guidelines based on our proxy advisor’s general global policies, regional codes of corporate governance, and our own views as investors in these markets. We apply a two-tier approach to determining and applying global proxy voting policies. The first tier establishes baseline policy guidelines for the most fundamental issues, which span the corporate governance spectrum without regard to a company’s domicile. The second tier takes into account various idiosyncrasies of different countries, making allowances for standard market practices, as long as they do not violate the fundamental goals of good corporate governance. The goal is to enhance shareholder value through effective use of the shareholder franchise, recognizing that application of a single set of policies is not appropriate for all markets.

Fixed Income and Passively Managed Strategies

Proxy voting for our fixed income and indexed portfolios is administered by the Global Proxy Operations team using T. Rowe Price’s guidelines as set by the TRPA ESG Investing Committee. Indexed strategies generally vote in line with the T. Rowe Price guidelines. Fixed income strategies generally follow the proxy vote determinations on security holdings held by our equity accounts unless the matter is specific to a particular fixed income security such as consents, restructurings, or reorganization proposals.

Shareblocking

Shareblocking is the practice in certain countries of “freezing” shares for trading purposes in order to vote proxies relating to those shares. In markets where shareblocking applies, the custodian or sub-custodian automatically freezes shares prior to a shareholder meeting once a proxy has been voted. T. Rowe Price’s policy is generally to refrain from voting shares in shareblocking countries unless the matter has compelling economic consequences that outweigh the temporary loss of liquidity in the blocked shares.

Securities on Loan

The Price Funds and our institutional clients may participate in securities lending programs to generate income for their portfolios. Generally, the voting rights pass with the securities on loan; however, lending agreements give the lender the right to terminate the loan and pull back the loaned shares provided sufficient notice is given to the custodian bank in advance of the applicable deadline. T. Rowe Price’s policy is generally not to vote securities on loan unless we determine there is a material voting event that could affect the value of the loaned securities. In this event, we have the discretion to pull back the loaned securities for the Price Funds in order to cast a vote at an upcoming shareholder meeting. A monthly monitoring process is in place to review securities on loan for the Price Funds and how they may affect proxy voting.

Monitoring and Resolving Conflicts of Interest

The TRPA ESG Investing Committee is also responsible for monitoring and resolving potential material conflicts between the interests of T. Rowe Price and those of its clients with respect to proxy voting. We have adopted safeguards to ensure that our proxy voting is not influenced by interests other than those of our fund shareholders and other investment advisory clients. While membership on the Committee is diverse, it does not include individuals whose primary duties relate to client relationship management, marketing, or sales. Since T. Rowe Price’s voting guidelines are predetermined by the Committee, application of the guidelines by portfolio managers to vote client proxies should in most instances adequately address any potential conflicts of interest. However, consistent with the terms of the Policies and Procedures, which allow portfolio managers to vote proxies opposite our general voting guidelines, the Committee regularly reviews all such proxy votes that are inconsistent with the proxy voting guidelines to determine whether the portfolio manager’s voting rationale appears reasonable. The Committee also assesses whether any business or other material relationships between T. Rowe Price and a portfolio company (unrelated to the ownership of the portfolio company’s securities) could have influenced an inconsistent vote on that company’s proxy. Issues raising potential conflicts of interest are referred to designated members of the Committee for immediate resolution prior to the time T. Rowe Price casts its vote.

With respect to personal conflicts of interest, T. Rowe Price’s Global Code of Conduct requires all employees to avoid placing themselves in a “compromising position” in which their interests may conflict with those of our clients and restrict their ability to engage in certain outside business activities. Portfolio managers or Committee members with a personal conflict of interest regarding a particular proxy vote must recuse themselves and not participate in the voting decisions with respect to that proxy.

Specific Conflict of Interest Situations

Voting of T. Rowe Price Group, Inc. common stock (sym: TROW) by certain T. Rowe Price Index Funds will be done in all instances in accordance with T. Rowe Price voting guidelines and votes inconsistent with the guidelines will not be permitted. In the event that there is no previously established guideline for a specific voting issue appearing on the T. Rowe Price Group proxy, the Price Funds will abstain on that voting item.