Wilburn J. Evans Form 4 FB Financial / Wilburn J. Evans ownership change

                               POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints
each of James R. Gordon and Beth W. Sims, or either of them signing singly, and
with full power of substitution, the undersigned's true and lawful attorney-in-
fact to:

(1)   to the extent necessary, prepare, execute in the undersigned's name
and on the undersigned's behalf, and submit to the U.S. Securities and Exchange
Commission (the "SEC") a Form ID, including amendments thereto, and any other
documents necessary or appropriate to obtain codes and passwords enabling the
undersigned to make electronic filings with the SEC of reports required by
Section 16(a) of the Securities Exchange Act of 1934 or any rule or regulation
of the SEC;

(2)   execute for and on behalf of the undersigned, in the undersigned's
capacity as beneficial owner of securities of FB Financial Corporation (the
"Company"), Form 144, 3, 4, 5 and any Schedules 13D or 13G in accordance with
Section 16(a) of the Securities Exchange Act of 1934, as amended, and the rules
thereunder;

(3)   do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to complete and execute any such Form 144,
3, 4, 5 and any Schedules 13D or 13G, complete and execute any amendment or
amendments thereto, and timely file any such form with the SEC and any stock
exchange or similar authority, including completing and executing a Uniform
Application for Access Codes to File on Edgar on Form ID; and

(4)   take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary, or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be
done by virtue of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934.

This Power of Attorney supersedes any power of attorney previously executed by
the undersigned regarding the purposes outlined in this Power of Attorney
("Prior Powers of Attorney"), and the authority of the attorneys-in-fact named
in any Prior Powers of Attorney is hereby revoked.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Form 144, 3, 4, 5 and any Schedules
13D or 13G with respect to the undersigned's holdings of and transactions in
securities issued by the Company, unless earlier revoked by the undersigned in a
signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 17th day of January, 2019.

                                        By: /s/ Wilburn J. Evans
                                            --------------------------------
                                        Name: Wilburn J. Evans
                                        Title: President, FirstBank Ventures