Exhibit 10.1

FIRST AMENDMENT  TO THIRD AMENDED AND RESTATED CREDIT AGREEMENT

This FIRST AMENDMENT TO THIRD AMENDED AND RESTATED CREDIT AGREEMENT (this "Amendment") is
effective as of May 28, 2020 (the "Effective Date"), by and among MAIN STREET CAPITAL CORPORATION, a Maryland corporation (the
"Borrower"), the GUARANTORS party to the Credit Agreement (as defined below) (the "Guarantors"), TRUIST
BANK (the "Administrative Agent") and the lenders party hereto (the "Lenders").

R E C I T A L S:

WHEREAS, the Borrower, the Guarantors, the Administrative Agent and the lenders party thereto have entered into that certain Third Amended and
Restated Credit Agreement dated as of June 5, 2018 (the "Credit Agreement"). Capitalized terms used in this Amendment that are not otherwise
defined in this Amendment shall have the respective meanings assigned to them in the Credit Agreement.

WHEREAS,
the Borrower and Guarantors have requested that the Administrative Agent and the Lenders amend the Credit Agreement. The Lenders, the Administrative Agent, the Borrower and the
Guarantors desire to amend the Credit Agreement upon the terms and conditions hereinafter set forth to modify Section 5.07 of the Credit Agreement.

NOW,
THEREFORE, in consideration of the Recitals and the mutual promises contained herein and for other good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Borrower, the Guarantors, the Administrative Agent and the Lenders, intending to be legally bound hereby, agree as follows:

SECTION 1.Recitals.The Recitals are incorporated herein by reference and shall be deemed to be a part
of this Amendment.

SECTION 2.Amendment to Section 5.07.Section 5.07 of the Credit Agreement is deleted in
its entirety and replaced with the following:



SECTION 3.Conditions to Effectiveness.The effectiveness of this Amendment and the obligations of the
Lenders hereunder are subject to the following conditions:



1

---





SECTION 4.No Other Amendment.Except for the amendments set forth in this Amendment, the text of the
Credit Agreement shall remain unchanged and in full force and effect. On and after the Effective Date, all references to the Credit Agreement in each of the Loan Documents shall hereafter mean the
Credit Agreement, as amended by this Amendment. This Amendment is not intended to effect, nor shall it be construed as, a novation. The Credit Agreement and this Amendment shall be construed together
as a single agreement. This Amendment shall constitute a Loan Document under the terms of the Credit Agreement. Nothing herein contained shall waive, annul, vary or affect any provision, condition,
covenant or agreement contained in the Credit Agreement, except as herein amended, nor affect or impair any rights, powers or remedies under the Credit Agreement as hereby amended. The Lenders and the
Administrative Agent do hereby reserve all of their rights and remedies against all parties who may be or may hereafter become secondarily liable for the repayment of the Obligations. The Borrower and
Guarantors promise and agree to perform all of the requirements, conditions, agreements and obligations under the terms of the Credit Agreement as heretofore and hereby amended, the Credit Agreement,
as amended, and the other Loan Documents being hereby ratified and affirmed. The Borrower and Guarantors hereby expressly agree that the Credit Agreement, as amended and the other Loan Documents are
in full force and effect.

2

---



SECTION 5.Representations and Warranties.The Borrower and Guarantors hereby represent and warrant to
the Administrative Agent and each of the Lenders as follows:



SECTION 6.Counterparts; Governing Law.This Amendment may be executed in multiple counterparts, each of
which shall be deemed to be an original and all of which, taken together, shall constitute one and the same agreement. This Amendment may be delivered by facsimile transmission or by electronic mail
with a .pdf copy or other replicating image attached, and any printed or copied version of any copy so delivered shall have the same force and effect as an originally signed counterpart. This
Amendment shall be construed in accordance with and governed by the law of the State of North Carolina.

SECTION 7.Amendment.This Amendment may not be amended or modified without the written consent of the
Required Lenders and the Administrative Agent.

SECTION 8.Further Assurances.The Loan Parties agree to promptly take such action, upon the request of
the Administrative Agent, as is necessary to carry out the intent of this Amendment.

SECTION 9.Consent by Guarantors.The Guarantors consent to the foregoing amendments. The Guarantors
promise and agree to perform all of the requirements, conditions, agreements and obligations under the terms of the Credit Agreement, as hereby amended, and the other Loan Documents to which they are
party, said Credit Agreement, as hereby amended, and such other Loan Documents being hereby ratified and affirmed. The Guarantors hereby expressly agree that the Credit Agreement, as hereby amended,
and the other Loan Documents are in full force and effect.

SECTION 10.Severability.Any provision of this Amendment that is prohibited or unenforceable in any
jurisdiction shall, as to such jurisdiction, be ineffective only to the extent of such prohibition or unenforceability without invalidating the remainder of such provision or the remaining provisions
hereof or thereof or affecting the validity or enforceability of such provision in any other jurisdiction.

SECTION 11.Notices.All notices, requests and other communications to any party to the Loan Documents,
as amended hereby, shall be given in accordance with the terms of Section 9.01 of the Credit Agreement.

[Remainder
of this page intentionally left blank]

3

---





IN
WITNESS WHEREOF, the parties hereto have executed and delivered, or have caused their respective duly authorized officers and representatives to execute and deliver, this Amendment as
of the day and year first above written.



BORROWER:MAIN STREET CAPITAL CORPORATIONBy:

/s/ BRENT D. SMITH

(SEAL)Name:

Brent D. SmithTitle:

Chief Financial Officer and TreasurerGUARANTORS:MAIN STREET CAPITAL PARTNERS, LLCBy:

/s/ BRENT D. SMITH

(SEAL)Name:

Brent D. SmithTitle:

Chief Financial Officer and TreasurerMAIN STREET EQUITY INTERESTS, INC.By:

/s/ BRENT D. SMITH

(SEAL)Name:

Brent D. SmithTitle:

Chief Financial Officer and TreasurerMS INTERNATIONAL HOLDINGS, INC.By:

/s/ BRENT D. SMITH

(SEAL)Name:

Brent D. SmithTitle:

Chief Financial Officer and TreasurerMAIN STREET CA LENDING, LLCBy:

/s/ BRENT D. SMITH

(SEAL)Name:

Brent D. SmithTitle:

Chief Financial Officer and Treasurer




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





TRUIST BANK,as Administrative AgentBy:

/s/ DAVID BENNETT

(SEAL)Name:

David BennettTitle:

Director




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





TRUIST BANK,as a LenderBy:

/s/ DAVID BENNETT

(SEAL)Name:

David BennettTitle:

Director




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





FROST BANK,as a LenderBy:

/s/ JAKE FITZPATRICK

(SEAL)Name:

Jake FitzpatrickTitle:

Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





ROYAL BANK OF CANADA,as a LenderBy:

/s/ GLENN VAN ALLEN

(SEAL)Name:

Glenn Van AllenTitle:

Authorized Signatory




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





HANCOCK WHITNEY BANK,as a LenderBy:

/s/ NATHANIEL ELLIS

(SEAL)Name:

Nathaniel EllisTitle:

Senior Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---







ZIONS BANCORPORATION, N.A. DBA AMEGY BANK,as a LenderBy:

/s/ MEGAN WIGINTON

(SEAL)Name:

Megan WigintonTitle:

Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





TEXAS CAPITAL BANK, N.A.,as a LenderBy:

/s/ EVA PAWELEK

(SEAL)Name:

Eva PawelekTitle:

Senior Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





CADENCE BANK, N.A.,as a LenderBy:

/s/ TAYLOR DUCOFF

(SEAL)Name:

Taylor DucoffTitle:

Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





COMERICA BANK,as a LenderBy:

/s/ L.J. PERENYI

(SEAL)Name:

L.J. PerenyiTitle:

Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





RAYMOND JAMES BANK, N.A.,as a LenderBy:

/s/ ALEXANDER L. RODY

(SEAL)Name:

Alexander L. RodyTitle:

Senior Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---







BOKF, NA DBA BANK OF TEXAS,as a LenderBy:

/s/ MARIAN LIVINGSTON

(SEAL)Name:

Marian LivingstonTitle:

Senior Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





WOODFOREST NATIONAL BANK,as a LenderBy:

/s/ ANDY GAINES

(SEAL)Name:

Andy GainesTitle:

Senior Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





CITY NATIONAL BANK,as a LenderBy:

/s/ ANDREW MILLER

(SEAL)Name:

Andrew MillerTitle:

Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





FIRST NATIONAL BANK OF PENNSYLVANIA,as a LenderBy:

/s/ CHARLES W. JONES

(SEAL)Name:

Charles W. JonesTitle:

Senior Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---





BANCORPSOUTH BANK,as a LenderBy:

/s/ PHILLIP M. GONZALEZ

(SEAL)Name:

Phillip M. GonzalezTitle:

Senior Vice President




[SIGNATURE PAGE TO FIRST AMENDMENT TO
THIRD AMENDED AND RESTATED CREDIT AGREEMENT]

---



QuickLinks