POWER OF ATTORNEY

           Know all by these presents that the undersigned, does hereby
make, constitute and appoint each of Thomas Szlosek, Justin Miller and Scott
Baker, or any one of them, as a true and lawful attorney-in-fact of the
undersigned with full powers of substitution and revocation, for and in the
name, place and stead of the undersigned (in the undersigned's individual
capacity), to execute and deliver such forms that the undersigned may be
required to file with the U.S. Securities and Exchange Commission as a result of
the undersigned's ownership of or transactions in securities of AVANTOR, INC.
(i) pursuant to Section 16(a) of the Securities Exchange Act of 1934, as
amended, including without limitation, statements on Form 3, Form 4 and Form 5
(including any amendments thereto) and (ii) in connection with any applications
for EDGAR access codes, including without limitation the Form ID. The Power of
Attorney shall remain in full force and effect until the undersigned is no
longer required to file Forms 3, 4 and 5 with regard to his or her ownership of
or transactions in securities of AVANTOR, INC., unless earlier revoked in
writing. The undersigned acknowledges that Thomas Szlosek, Justin Miller and
Scott Baker are not assuming any of the undersigned's responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934, as amended.

            By: /s/Christophe Couturier
                -----------------------
                Name: Christophe Couturier


            Date: April 29, 2019