POWER OF ATTORNEY

The undersigned officer or director of Exxon Mobil Corporation,
a New Jersey corporation ("ExxonMobil"), constitutes and
appoints Cynthia K. Guild, J. Powell Fancher, and Lisa K. Bork, and
each of them, as his or her true and lawful attorneys-in-fact
and agents, with full power of substitution and resubstitution,
for him or her and in his or her name, place and stead, in any
and all capacities, to sign any and all forms of report with
respect to securities of ExxonMobil required under Section
16(a) of the Securities Exchange Act of 1934, as amended, and
to file the same, and any other documents in connection
therewith, with the Securities and Exchange Commission, any
stock exchange and ExxonMobil, granting unto said
attorneys-in-fact and agents, and each of them, full power
and authority to do and perform each and every act and thing
requisite and necessary to be done, as fully for all intents
and purposes as he or she might or could do in person, hereby
ratifying and confirming all that said attorneys-in-fact and
agents or any of them or their or his or her substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

This power of attorney shall remain in effect until the
undersigned is no longer required to file forms of report
with respect to securities of Exxon Mobil Corporation under
Section 16(a) of the Securities Exchange Act of 1934, as
amended, unless earlier revoked by the undersigned in a signed
writing delivered to the foregoing attorneys-in-fact.
Effective as of the date of this power of attorney, the
undersigned hereby revokes any and all earlier-dated powers
of attorney given by the undersigned with respect to
ExxonMobil securities reporting under said Section 16(a).

IN WITNESS WHEREOF, the undersigned has executed this power of
attorney as of the date set forth below.


   29 March 2021           /s/ Jack P. Williams, Jr.
     Date	              Jack P. Williams, Jr.

   Irving, TX
 Location (City, State)