Item 1. Reports to Stockholders.

(a)         

Table of Contents

PERFORMANCE as of June 30, 2026

​(1)    The Fund commenced operations on July 2, 2017. Performance prior to November 23, 2020 is of the predecessor fund, Flat Rock Capital Corp.

​(2)    Performance returns are net of management fees and other Fund expenses.

​(3)    The return shown is based on net asset value (“NAV”) calculated for shareholder transactions and may differ from the return shown in the Financial Highlights, which reflects adjustments made to the NAV in accordance with accounting principles generally accepted in the United States of America.

​(4)    The Bloomberg US Aggregate Bond Index is a broad-based, market capitalization-weighted bond market index representing intermediate-term investment grade bonds traded in the United States.

​(5)    The Bloomberg US Corporate High Yield Bond Index measures the USD-denominated, high yield, fixed-rate corporate bond market.

​(6)    The Morningstar LSTA US Leveraged Loan Index is a market value weighted index designed to capture the performance of the US leveraged loan market.

Performance data quoted represents past performance, which is not a guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, if repurchased by the Fund, may be worth more or less than their original cost. Total return measures net investment income and capital gain or loss from portfolio investments. All performance shown assumes reinvestment of dividends and capital gains distributions.

The Fund is a continuously offered, diversified, closed-end management investment company that is operated as an interval fund. The Fund is suitable only for investors who can bear the risks associated with the Fund’s limited liquidity and should be viewed as a long-term investment. The Fund’s shares have no history of public trading, nor is it intended that its shares will be listed on a national securities exchange at this time, if ever. Investing in the Fund’s shares may be speculative and involves a high degree of risk, including the risk associated with below-investment grade securities and leverage. Investing in the Fund involves risk, including the risk that shareholders may receive little or no return on their investment or that shareholders may lose part or all of their investment. The Fund intends to invest primarily in the senior secured loans of U.S. middle-market companies. The Fund may also invest in the junior debt (and to a lesser extent, the equity) tranches of collateralized loan obligations (“CLOs”) that provide exposure to senior secured loans of middle-market companies. The Fund’s investments in the equity and junior debt tranches of CLOs are exposed to leveraged credit risk. Investments in the lowest tranches bear the highest level of risk. The Fund may pay

distributions in significant part from sources that may not be available in the future and that are unrelated to its performance, such as a return of capital or borrowings. The amount of distributions that the Fund may pay, if any, is uncertain.

ASSET ALLOCATION as of June 30, 2026*

*      Holdings are subject to change.

        Percentages are based on net assets of the Fund.

TOP TEN HOLDINGS* as of June 30, 2026

*      Holdings are subject to change and exclude cash equivalents.

GROWTH OF A HYPOTHETICAL $10,000 INVESTMENT

The graph below illustrates the growth of a hypothetical $10,000 investment assuming the purchase of common shares at the NAV of $20.00 on July 2, 2017 (commencement of operations) and tracking its progress through June 30, 2026.

The hypothetical $10,000 investment at inception includes changes due to share price and reinvestment of dividends and capital gains. The chart does not imply future performance. Indexes are unmanaged, do not incur fees, expenses or taxes, and cannot be invested in directly. Performance quoted does not include a deduction for taxes that a shareholder would pay on the repurchase of its shares by the Fund. Performance prior to November 23, 2020 is of the predecessor fund, Flat Rock Capital Corp.

​(a)    The level 3 assets were a result of unavailable quoted prices from an active market or the unavailability of other significant observable inputs.

​(b)    Securities are exempt from registration under the Securities Act of 1933 and are deemed to be “restricted” securities. As of June 30, 2026, the total fair value of these securities amounts to $176,499,688, which represents 61.51% of net assets.

​(c)    Variable rate security. Interest rate resets periodically. The rate shown is the effective interest rate as of June 30, 2026. For securities based on a published reference rate and spread, the reference rate and spread (in basis points) are indicated parenthetically. Certain variable rate securities are not based on a published reference rate and spread but are determined by the issuer or agent and are based on current market conditions. These securities, therefore, do not indicate a reference rate and spread.

​(d)    CLO equity positions are entitled to recurring distributions, which are generally equal to the remaining cash flow of payments made by underlying securities less contractual payments to debt holders and CLO expenses. The effective yield is estimated based upon the current projection of the amount and timing of these recurring distributions in addition to the estimated amount of terminal principal payment. Effective yields for the CLO equity positions are updated generally once a quarter or in connection with a transaction such as an add-on purchase, refinancing or reset. The estimated yield and investment cost may ultimately not be realized. Total fair value of the securities is $16,489,021, which represents 5.75% of net assets as of June 30, 2026.

​(e)    Equity tranches in securitizations of limited partnership interests in a loan fund (“Feeder Fund Investments — Equity”) are entitled to recurring distributions, which are generally equal to the remaining cash flow of payments made by the underlying loan fund less contractual payments to debt holders and fund expenses. The effective yield is estimated based upon the current projections of the amount and timing of these recurring distributions in addition to the estimated amount of the terminal principal payment. Effective yields are generally updated once a quarter or in connection with events such as an add-on purchase, refinancing or reset. The estimated yield and investment cost may ultimately not be realized. As of June 30, 2026, the total fair value of Feeder Fund Investments — Equity was $13,250,000, representing 4.62% of net assets.

​(f)    Debt tranches in securitizations of limited partnership interests in a loan fund (“Feeder Fund Investments — Debt”) are entitled to contractual interest payments derived from the cash flows generated by the underlying loan fund. As of June 30, 2026, the total fair value of Feeder Fund Investments — Debt was $6,553,865, representing 2.28% of net assets.

​(g)    All or a portion of the security has been pledged as collateral in connection with the credit facility with certain funds and accounts managed by Cadence Bank, N.A. (the “Credit Facility”). At June 30, 2026, the value of securities pledged amounted to $138,191,147, which represents approximately 48.16% of net assets, and 37.84% of total assets.

​(h)    Investment has been committed to but has not been funded by the Fund as of June 30, 2026.

​(i)    Facility is currently winding down.

​(j)         A portion of the stated interest rate is payment-in-kind.

​(k)        Investment was acquired via participation agreement.

​(l)         Non-income producing security.

​(m)       Security received at zero cost through a restructuring of previously held debt securities.

​(n)        Investment does not issue shares.

​(o)        Rate disclosed is the seven-day effective yield as of June 30, 2026.

Investment Abbreviations:

SOFR – Secured Overnight Financing Rate

PIK – Payment-In-Kind

Reference Rates: 

1M US SOFR – 1 Month SOFR as of June 30, 2026 was 3.65%.

3M US SOFR – 3 Month SOFR as of June 30, 2026 was 3.73%.

​(a)    $10,000 liquidation value per share. 1,000 shares authorized, issued and outstanding.

*      Includes adjustments in accordance with accounting principles generally accepted in the United States and, consequently, the NAV for financial reporting purposes and the returns based upon those NAV may differ from the NAV and returns for shareholder transactions.

​(a)        Based on average shares outstanding during the period.

​(b)        The amount shown for a share outstanding throughout the period does not accord with the change in aggregate gains and losses in the portfolio of securities during the period due to the timing of sales and purchases of Fund shares in relation to fluctuating market values during the period.

​(c)        Total return in the above table represents the rate that the investor would have earned or lost on an investment in the Fund, assuming reinvestment of dividends.

​(d)        Not annualized.

​(e)        Includes a contribution from affiliate. If the affiliate had not made the contribution, total return would have been 3.21%.

​(f)         Interest expense relates to the Fund’s Credit Facility (see Note 9) and includes amortization of debt issuance costs as well as dividends on mandatorily redeemable preferred stock (see Note 10).

​(g)        Annualized.

​(h)        The ratio of expenses to average net assets including fee waivers includes $1,231,118 in voluntary advisory fee waivers representing (0.39)%. This voluntary waiver is not subject to recoupment.

​(i)         The ratio of expenses to average net assets including fee waivers includes $189,344 in voluntary advisory fee waivers representing (0.07)%. This voluntary waiver is not subject to recoupment.

​(j)         Calculated by subtracting the Fund’s total liabilities (excluding the Credit Facility and accumulated unpaid interest on Credit Facility) from the Fund’s total assets and dividing by the outstanding Credit Facility balance.

​(k)        Asset coverage ratio is calculated by subtracting the Fund’s total liabilities (excluding the liquidation value of the Fund’s mandatorily redeemable preferred stock including distributions payable on the Fund’s mandatorily redeemable preferred stock) from the Fund’s total assets and dividing by the liquidation value of the Fund’s mandatorily redeemable preferred stock. The asset coverage per share figure is expressed in terms of dollar amounts per share of outstanding preferred stock.

Flat Rock Core Income Fund (the “Fund”) is registered under the Investment Company Act of 1940, as amended, (the “1940 Act”) as a diversified, closed-end management investment company. The shares of beneficial interest of the Fund (the “Shares”) are continuously offered under Rule 415 under the Securities Act of 1933, as amended (the “Securities Act”). The Fund operates as an interval fund pursuant to Rule 23c-3 under the 1940 Act and has adopted a fundamental policy to conduct quarterly repurchase offers at net asset value (“NAV”).

The Fund’s investment objective is the preservation of capital while generating current income from its investments and seeking to maximize the portfolio’s total return.

The Fund was formed as a Delaware statutory trust on June 11, 2020, and operates pursuant to a Second Amended and Restated Agreement and Declaration of Trust governed by and interpreted in accordance with the laws of the State of Delaware. The Fund had no operations from that date to November 23, 2020, other than those related to organizational matters and the registration of its Shares under applicable securities laws.

FRC Funding I, LLC (“FRC Funding”), the Fund’s wholly owned financing subsidiary, is consolidated in the Fund’s financial statements.

The Fund has adopted Financial Accounting Standards Board (“FASB”) Accounting Standards Update 2023-07, Segment Reporting (Topic 280) — Improvements to Reportable Segment Disclosures (“Topic 280”). Adoption of the standard impacted financial statement disclosures only and did not affect the Fund’s financial position or the results of its operations. An operating segment is defined in Topic 280 as a component of a public entity that engages in business activities from which it may recognize revenues and incur expenses, has operating results that are regularly reviewed by the public entity’s chief operating decision maker (“CODM”) to make decisions about resources to be allocated to the segment and assess its performance, and has discrete financial information available. The Fund’s CODM is the President and Chief Executive Officer of the Fund. The Fund operates as a single operating segment. The Fund’s income, expenses, assets, changes in net assets resulting from operations and performance are regularly monitored and assessed as a whole by the CODM responsible for oversight functions of the Fund, using the information presented in the financial statements and financial highlights.

The following is a summary of significant accounting policies followed by the Fund in preparation of its financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The Fund is an investment company under U.S. GAAP and follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 946.

Use of Estimates: The preparation of the financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of increases and decreases in net assets from operations during the period. Actual results could differ from these estimates.

Preferred Shares: In accordance with ASC 480-10-25, the Fund’s mandatorily redeemable preferred stock has been classified as debt on the Consolidated Statement of Assets and Liabilities. Refer to “Note 10. Mandatorily Redeemable Preferred Stock” for further details.

Security Valuation: The Fund determines the NAV of its shares daily as of the close of regular trading (normally, 4:00 p.m., Eastern time) on each day that the New York Stock Exchange (“NYSE”) is open for business.

The 1940 Act requires the Fund to determine the value of its portfolio securities using market quotations when “readily available,” and when market quotations are not readily available, portfolio securities must be valued at fair value, as determined in good faith by the Fund’s board of trustees (the “Board”). As stated in Rule 2a-5 under the 1940 Act (“Rule 2a-5”), determining fair value in good faith requires (i) assessment and management of risks, (ii) establishment of fair value methodologies, (iii) testing of fair value methodologies, and (iv) evaluation of pricing services. Under Rule 2a-5, a fund’s board may designate the fund’s adviser as “valuation designee” to perform fair value determinations. The Board, including a majority of the trustees who are not “interested persons” of the Fund, as such term is defined in the 1940 Act, has designated Flat Rock Global, LLC (the “Adviser”) to perform fair value determinations and act as “valuation designee” for the Fund’s investments.

The Fund records its investments at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The valuation techniques used to determine fair value are further discussed below.

It is the policy of the Fund to value its portfolio securities using market quotations when readily available. For purposes of this policy, a market quotation is readily available only when that quotation is a quoted price (unadjusted) in active markets for identical investments that the Fund can access at the measurement date, provided that a quotation will not be readily available if it is not reliable. If market quotations are not readily available, securities or other assets will be valued at their fair market value as determined using the valuation methodologies approved by the Board.

Equity securities for which market quotations are available are generally valued at the last sale price or official closing price on the primary market or exchange on which they trade.

Short-term debt securities having a remaining maturity of 60 days or less when purchased are valued at cost adjusted for amortization of premiums and accretion of discounts, which approximates fair value.

The Fund primarily invests directly in senior secured loans of U.S. middle-market companies (“Senior Loans”) (either in the primary or secondary markets). The Fund’s Senior Loans are valued without accrued interest, and accrued interest is reported as income in the Fund’s Consolidated Statement of Operations.

Certain of the Senior Loans held by the Fund will be broadly syndicated loans. Broadly syndicated loans will be valued by using readily available market quotations or indicative market quotations provided by an independent, third-party pricing service.

For each Senior Loan held by the Fund, that is either: 1) not a broadly syndicated loan; or 2) is a broadly syndicated loan but has limited liquidity such that the Adviser determines that readily available or indicative market quotations do not reflect fair value, the Adviser will employ the methodology it deems most appropriate to fair value the Senior Loan. For the period before such a Senior Loan begins providing quarterly financial updates, the Senior Loan’s fair value will usually be listed as the cost at which the Fund purchased the Senior Loan. For all other such Senior Loans, the Adviser will fair value each of these on a quarterly basis after the underlying portfolio company has reported its most recent quarterly financial update. These fair value calculations involve significant professional judgment by the Adviser

program for the Fund consistent with the Fund’s investment objective and strategies. As compensation for its management services, the Fund pays the Adviser a management fee of 1.375% (as a percentage of the average daily value of net assets), paid monthly in arrears, calculated based on the average daily value of net assets during such period. Prior to February 28, 2025, the management fee was calculated and payable monthly in arrears at the annual rate of 1.375% of the Fund’s average daily total assets during such period.

In addition to the management fee, the Adviser is entitled to an incentive fee. The incentive fee is calculated and payable quarterly in arrears in an amount equal to 15.0% of the Fund’s “pre-incentive fee net investment income” for the immediately preceding quarter, and is subject to a hurdle rate, expressed as a rate of return on the Fund’s “adjusted capital,” equal to 1.50% per quarter (or an annualized hurdle rate of 6.00%), subject to a “catch-up” feature, which allows the Adviser to recover foregone incentive fees that were previously limited by the hurdle rate. For this purpose, “pre-incentive fee net investment income” means interest income, dividend income and any other income (including any other fees such as commitment, origination, structuring, diligence and consulting fees or other fees that the Fund receives from portfolio companies) accrued during the calendar quarter, minus the Fund’s operating expenses for the quarter (including the base management fee, expenses reimbursed to the Adviser and any interest expense and dividends paid on any issued and outstanding preferred stock, but excluding the incentive fee). Pre-incentive fee net investment income includes, in the case of investments with a deferred interest feature (such as original issue discount, debt instruments with payment-in-kind interest and zero-coupon securities), accrued income that the Fund has not yet received in cash. Pre-incentive fee net investment income does not include any realized capital gains, realized capital losses or unrealized capital appreciation or depreciation. “Adjusted capital” means the cumulative gross proceeds received by the Fund from the sale of Shares (including pursuant to the Fund’s distribution reinvestment policy), reduced by amounts paid in connection with purchases of the Fund’s Shares pursuant to the Fund’s repurchase program. Effective July 1, 2026, the Board approved an amendment to the Advisory Agreement to change the basis of the “pre-incentive fee net investment income” calculation from “adjusted capital” to net asset value.

The calculation of the incentive fee on pre-incentive fee net investment income for each quarter is as follows:

•     No incentive fee is payable in any calendar quarter in which the Fund’s pre-incentive fee net investment income does not exceed the hurdle rate of 1.50% per quarter (or an annualized rate of 6.00%);

•     100% of the Fund’s pre-incentive fee net investment income, if any, that exceeds the hurdle rate but is less than or equal to 1.764%. This portion of the Fund’s pre-incentive fee net investment income (which exceeds the hurdle rate but is less than or equal to 1.764%) is referred to as the “catch-up.” The “catch-up” provision is intended to provide the Adviser with an incentive fee of 15.0% on all of the Fund’s pre-incentive fee net investment income when the Fund’s pre-incentive fee net investment income reaches 1.764% in any calendar quarter; and

•     15.0% of the amount of the Fund’s pre-incentive fee net investment income, if any, that exceeds 1.764% in any calendar quarter is payable to the Adviser once the hurdle rate is reached and the catch-up is achieved (15.0% of all pre-incentive fee net investment income thereafter will be allocated to the Adviser).

For the six months ended June 30, 2026, the Adviser earned $2,007,524 in management fees and $2,029,571 in incentive fees.