POWER OF ATTORNEY

      Know all by these presents that the undersigned, John L. MacCarthy, hereby
constitutes and appoints William M. Miller, James E. Sinople and/or Shalinni
Thompson of Nuveen Global Cities REIT, Inc. (the "Company") the undersigned's
true and lawful attorney-in-fact to:

      1.    prepare, execute in the undersigned's name and on the undersigned's
            behalf, and submit to the U.S. Securities and Exchange Commission
            ("SEC") a Form ID application, including any 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, as amended (the "Exchange Act"), or any rule
            or regulation of the SEC (the "Form ID");

      2.    execute for and on behalf of the undersigned, in the undersigned's
            capacity as a director or officer of the Company, Forms 3, 4 and 5,
            and any amendments thereto (the "Section 16 Reports"), in accordance
            with Section 16(a) of the Exchange Act and the rules thereunder (the
            "Section 16 Law"); and

      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 the Form
            ID and any such Section 16 Reports, and file (or cause to be filed)
            the same with the SEC.

      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 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 attorney-in-fact, in
serving in such capacity at the request of the undersigned, is not assuming, nor
is the Company assuming, any of the undersigned's responsibilities to comply
with the Section 16 Law.

      This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to sign any Section 16 Reports 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 Company. In affixing his signature to this Power of Attorney, the
undersigned hereby revokes any and all previously executed Powers of Attorney
for the same or similar purposes.

      IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 26th day of February, 2021.


               Signature:   /s/ John L. MacCarthy
                            ----------------------------
               Name:        John L. MacCarthy
                            ----------------------------