POWER OF ATTORNEY

(For Executing Form ID and Forms 3, 4 and 5)

	Know all by these presents, that the undersigned hereby constitutes and
appoints Aaron Saltz, David Day and Shawna Hughes of Magnite, Inc. (the
"Company"), signing individually, as the undersigned's true and lawful
attorneys-in fact and agents to:

	(1)	Prepare, execute in the undersigned's name and on the undersigned's behalf,
and submit to the Securities and Exchange Commission (the "SEC") Form ID and
Forms 3, 4 and 5 (including amendments thereto and joint filing agreements in
connection therewith) in accordance with Section 16(a) of the Securities
Exchange Act of 1934, as amended (the "Exchange Act") and the rules thereunder
in the undersigned's capacity as an officer, director or beneficial owner of
more than 10% of a registered class of securities of the Company;

	(2)	Do and perform any and all acts for and on behalf of the undersigned that
may be necessary or desirable to prepare and execute any such Form ID or Forms
3, 4 or 5 (including amendments thereto and joint filing agreements in
connection therewith) and file such forms with the SEC and any stock exchange,
self-regulatory association or any similar authority; and

	(3)	Take any other action of any type whatsoever in connection with the
foregoing that, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required of the undersigned, it being
understood that the documents executed by the 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 the attorney-in-fact may approve in the
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, and their
substitutes, 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 Exchange Act.

	This Power of Attorney shall remain in full force and effect until the earliest
to occur of (a) the undersigned is no longer required to file Form ID or Forms
3, 4 and 5 with respect to the undersigned's holdings of and transactions in
securities issued by the Company, (b) revocation by the undersigned in a signed
writing delivered to the Company and the foregoing attorneys-in fact or (c) as
to any attorney-in-fact individually, until such attorney-in-fact is no longer
employed by the Company.

	IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of the date written below.

Dated: May 26, 2021

By: /s/ James Allen Dove
Name:  James Allen Dove