UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT

INVESTMENT COMPANIES

Investment Company Act file number: 811-22061

Name and address of agent for service: John M. Perlowski, Chief Executive Officer, BlackRock Funds II, 55 East 52^nd Street, New York, NY 10055

Registrant’s telephone number, including area code: (800) 441-7762

Date of fiscal year end: 05/31/2023

Date of reporting period: 11/30/2022

Item 1 – Report to Stockholders

(a) The Report to Shareholders is attached herewith.

BlackRock Funds II

· BlackRock Global Dividend Portfolio

BlackRock Series, Inc.

· BlackRock International Fund

Table of Contents

Investment Objective

BlackRock Global Dividend Portfolio’s (the “Fund”) investment objective is to seek to provide a level of current income that exceeds the average yield on global stocks generally. Additionally, the Fund seeks to provide long-term capital appreciation.

Portfolio Management Commentary

How did the Fund perform?

For the six-month period ended November 30, 2022, the Fund underperformed its benchmark, the MSCI All Country World Index.

What factors influenced performance?

The Fund’s stock selection in information technology was one of the largest detractors from relative performance at the sector level. Among individual positions, Fidelity National Information Services was the main detractor, as it meaningfully reset expectations for long-term growth rates in its merchant business due to market-share losses in the small and mid-sized business segment. Lower growth disappointed investors, and the high profitability of the small and medium business segment raised concerns about margin degradation. The Fund exited its position as management has not provided enough granularity about these margin impacts, making the range of outcomes too wide to feel comfortable that the stock price has hit bottom. Assurant also weighed on relative performance as it faced two business challenges. First, high inflation has caused higher claims costs in its global housing business, and while margins will recover in time, there is a lag before pricing can adjust accordingly. Second, Assurant’s “Connected Living” consumer business has grown more slowly than expected due to a cautious consumer spending environment. Lastly, pharmaceutical company Sanofi was a top detractor from relative performance amid recent litigation concerns about the recalled drug Zantac. Sanofi owned and distributed Zantac for two years, but a number of other companies have produced and distributed the drug since its approval, making the implications for legal liability unclear and causing weakness in the share price during the period.

Conversely, the largest contributors to the Fund’s relative performance at the sector level were stock selection decisions among consumer discretionary stocks, a lack of exposure to the real estate sector, and an underweight allocation to materials. AbbVie was the top individual contributor to relative performance, as its defensive characteristics proved beneficial in the volatile market environment. AbbVie’s stock also reacted positively to incrementally positive data on its rheumatoid arthritis drug Humira. Elsewhere, EssilorLuxottica also contributed, as it showed resilient performance in earnings growth and margins through a challenging inflationary period, due in part to the benefits of its vertically integrated supply chain. Inelastic consumer demand for eyeglasses also makes EssilorLuxottica a defensive stock, and the company has relatively low exposure to China, whose economy has been weak throughout the period. Lastly, UnitedHealth Group also contributed as a defensive stock providing resilience in a bear market. UnitedHealth’s collaboration with retail giant Walmart to provide affordable health care services also helped boost the stock’s performance.

Describe recent portfolio activity.

The most significant change in the Fund’s positioning was a reduction in the communication services sector, which resulted from the sale of its position in Comcast. The Fund also reduced exposure to financials and utilities, cutting positions in M&T Bank and EDP respectively. Conversely, the Fund increased exposure to materials and industrials by buying positions in Air Liquide and United Parcel Service respectively. The Fund also boosted its exposure to healthcare with new positions in EssilorLuxxotica and Lonza.

Describe portfolio positioning at period end.

The Fund’s largest overweight sector exposures were to health care, consumer staples, and industrials. Conversely, the Fund was underweight consumer discretionary, real estate, and materials. From a regional perspective, the majority of the portfolio was listed in Europe and North America, with large overweight exposures to the United Kingdom, France, and Switzerland. The largest underweight exposures were to the United States, Japan, and China, despite more than 45% of the portfolio being listed in the United States.

The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.

Performance

N/A - Not applicable as share class and index do not have a sales charge.

Past performance is not an indication of future results.

Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles.

Expense Example

Portfolio Information

Investment Objective

BlackRock International Fund’s (the “Fund”) investment objective is to seek long-term capital growth through investments primarily in a diversified portfolio of equity securities of companies located outside the United States.

Portfolio Management Commentary

How did the Fund perform?

For the six-month period ended November 30, 2022, all of the Fund’s share classes underperformed its benchmark, the MSCI All Country World Index ex-USA.

What factors influenced performance?

Stock selection within materials, industrials, and communication services were the top detractors from relative return at the sector level. Among individual securities, DSM, Sanofi, and Cellnex were the primary detractors. DSM’s profit margins fell severely due to inflation and high energy costs in Europe, as well as a generally struggling biotech industry. The long lead time for DSM to close its deal with Firmenich also kept the stock under pressure. Sanofi was a top detractor from relative performance amid recent litigation concerns about the recalled drug Zantac. Sanofi owned and distributed Zantac for two years, but a number of other companies have produced and distributed the drug since its approval, making the implications for legal liability unclear and causing weakness in the share price during the period. Lastly, Cellnex faced consequences similar to its mobile tower company peers from rapidly rising interest rates, as high debt levels significantly increase costs of capital.

Conversely, stock selection within the information technology, financials, and real estate sectors were the top contributors to relative return. At the individual security level, Daiichi Sankyo, Novo Nordisk, and UniCredit were the top relative contributors. Daiichi reported multiple positive developments, including a victory in its arbitration case against Seagen that included a favorable ruling on its technology, along with encouraging progress from lung cancer candidate treatment Enhertu, on which investors await phase 3 clinical trial results. Novo Nordisk’s defensive qualities contributed to performance, as did continuing upward earnings momentum and rising expectations for its obesity treatment Wegovy. Lastly, UniCredit made multiple share repurchases, including one in September 2022 covering 4.3% of its outstanding capital. The stock rose sharply despite tensions between it and the European Central Bank concerning its presence in Russia.

Describe recent portfolio activity.

The largest change in positioning was an increase in consumer discretionary exposure, followed by additions to healthcare and consumer staples. Conversely, the Fund reduced exposure to the industrials, communication services, and materials sectors.

Describe portfolio positioning at period end.

The Fund’s largest sector overweights at period end were in healthcare, industrials, and communication services. The largest underweights were in financials, consumer staples, and utilities. From a geographic perspective, the Fund’s largest country overweights were to the United States, the Netherlands, and Italy, while the largest underweights were in United Kingdom, China, and Australia.

The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.

Performance

N/A - Not applicable as share class and index do not have a sales charge.

Past performance is not an indication of future results.

Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles.

Expense Example

Portfolio Information

About Fund Performance

Institutional and Class K Shares are not subject to any sales charge. These shares bear no ongoing distribution or service fees and are available only to certain eligible investors. Class K Shares performance shown prior to the Class K Shares inception date of January 25, 2018 for BlackRock International Fund and June 8, 2016 for BlackRock Global Dividend Portfolio is that of Institutional Shares. The performance of each Fund’s Class K Shares would be substantially similar to Institutional Shares because Class K Shares and Institutional Shares invest in the same portfolio of securities and performance would only differ to the extent that Class K Shares and Institutional Shares have different expenses. The actual returns of Class K Shares would have been higher than those of the Institutional Shares because Class K Shares have lower expenses than the Institutional Shares.

Investor A Shares are subject to a maximum initial sales charge (front-end load) of 5.25% and a service fee of 0.25% per year (but no distribution fee). Certain redemptions of these shares may be subject to a contingent deferred sales charge (“CDSC”) where no initial sales charge was paid at the time of purchase. These shares are generally available through financial intermediaries.

Investor C Shares are subject to a 1.00% CDSC if redeemed within one year of purchase. In addition, these shares are subject to a distribution fee of 0.75% per year and a service fee of 0.25% per year. These shares are generally available through financial intermediaries. These shares automatically convert to Investor A Shares after approximately eight years.

Class R Shares (available only in BlackRock International Fund) are not subject to any sales charge. These shares are subject to a distribution fee of 0.25% per year and a service fee of 0.25% per year. These shares are available only to certain employer-sponsored retirement plans.

Past performance is not an indication of future results. Financial markets have experienced extreme volatility and trading in many instruments has been disrupted. These circumstances may continue for an extended period of time and may continue to affect adversely the value and liquidity of each Fund’s investments. As a result, current performance may be lower or higher than the performance data quoted. Refer to blackrock.com to obtain performance data current to the most recent month-end. Performance results do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption of Fund shares. Figures shown in the performance tables assume reinvestment of all distributions, if any, at net asset value (“NAV”) on the ex-dividend date or payable date, as applicable. Investment return and principal value of shares will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Distributions paid to each class of shares will vary because of the different levels of service, distribution and transfer agency fees applicable to each class, which are deducted from the income available to be paid to shareholders.

BlackRock Advisors, LLC (the “Manager”), each Fund’s investment adviser, has contractually and/or voluntarily agreed to waive and/or reimburse a portion of each Fund’s expenses. Without such waiver(s) and/or reimbursement(s), each Fund’s performance would have been lower. With respect to each Fund’s voluntary waiver(s), if any, the Manager is under no obligation to waive and/or reimburse or to continue waiving and/or reimbursing its fees and such voluntary waiver(s) may be reduced or discontinued at any time. With respect to each Fund’s contractual waiver(s), if any, the Manager is under no obligation to continue waiving and/or reimbursing its fees after the applicable termination date of such agreement. See the Notes to Financial Statements for additional information on waivers and/or reimbursements.

Disclosure of Expenses

Shareholders of each Fund may incur the following charges: (a) transactional expenses, such as sales charges; and (b) operating expenses, including investment advisory fees, administration fees, service and distribution fees, including 12b-1 fees, acquired fund fees and expenses, and other fund expenses. The expense examples shown (which are based on a hypothetical investment of $1,000 invested at the beginning of the period and held through the end of the period) are intended to assist shareholders both in calculating expenses based on an investment in each Fund and in comparing these expenses with similar costs of investing in other mutual funds.

The expense examples provide information about actual account values and actual expenses. Annualized expense ratios reflect contractual and voluntary fee waivers, if any. In order to estimate the expenses a shareholder paid during the period covered by this report, shareholders can divide their account value by $1,000 and then multiply the result by the number corresponding to their Fund and share class under the heading entitled “Expenses Paid During the Period.”

The expense examples also provide information about hypothetical account values and hypothetical expenses based on a Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses. In order to assist shareholders in comparing the ongoing expenses of investing in these Funds and other funds, compare the 5% hypothetical examples with the 5% hypothetical examples that appear in shareholder reports of other funds.

The expenses shown in the expense examples are intended to highlight shareholders’ ongoing costs only and do not reflect transactional expenses, such as sales charges, if any. Therefore, the hypothetical examples are useful in comparing ongoing expenses only, and will not help shareholders determine the relative total expenses of owning different funds. If these transactional expenses were included, shareholder expenses would have been higher.

Derivative Financial Instruments

BlackRock International Fund may invest in various derivative financial instruments. These instruments are used to obtain exposure to a security, commodity, index, market, and/or other assets without owning or taking physical custody of securities, commodities and/or other referenced assets or to manage market, equity, credit, interest rate, foreign currency exchange rate, commodity and/or other risks. Derivative financial instruments may give rise to a form of economic leverage and involve risks, including the imperfect correlation between the value of a derivative financial instrument and the underlying asset, possible default of the counterparty to the transaction or illiquidity of the instrument. Pursuant to Rule 18f-4 under the 1940 Act, among other things, the Fund must either use derivative financial instruments with embedded leverage in a limited manner or comply with an outer limit on fund leverage risk based on value-at-risk. The Fund’s successful use of a derivative financial instrument depends on the investment adviser’s ability to predict pertinent market movements accurately, which cannot be assured. The use of these instruments may result in losses greater than if they had not

Derivative Financial Instruments    (continued)

been used, may limit the amount of appreciation the Fund can realize on an investment and/or may result in lower distributions paid to shareholders. The Fund’s investments in these instruments, if any, are discussed in detail in the Notes to Financial Statements.

Affiliates

Investments in issuers considered to be affiliate(s) of the Fund during the six months ended November 30, 2022 for purposes of Section 2(a)(3) of the Investment Company Act of 1940, as amended, were as follows:

Fair Value Hierarchy as of Period End

Various inputs are used in determining the fair value of financial instruments. For a description of the input levels and information about the Fund’s policy regarding valuation of financial instruments, refer to the Notes to Financial Statements.

The following table summarizes the Fund’s financial instruments categorized in the fair value hierarchy. The breakdown of the Fund’s financial instruments into major categories is disclosed in the Schedule of Investments above.

See notes to financial statements.

Affiliates

Investments in issuers considered to be affiliate(s) of the Fund during the six months ended November 30, 2022 for purposes of Section 2(a)(3) of the Investment Company Act of 1940, as amended, were as follows:

Forward Foreign Currency Exchange Contracts

Derivative Financial Instruments Categorized by Risk Exposure

As of period end, the fair values of derivative financial instruments located in the Statements of Assets and Liabilities were as follows:

For the period ended November 30, 2022, the effect of derivative financial instruments in the Statements of Operations was as follows:

Average Quarterly Balances of Outstanding Derivative Financial Instruments

For more information about the Fund’s investment risks regarding derivative financial instruments, refer to the Notes to Financial Statements.

Derivative Financial Instruments – Offsetting as of Period End

The Fund’s derivative assets and liabilities (by type) were as follows:

The following table presents the Fund’s derivative assets and liabilities by counterparty net of amounts available for offset under an MNA and net of the related collateral received and pledged by the Fund: