LIMITED POWER OF ATTORNEY FOR
SECTION 16 REPORTING OBLIGATIONS


Know all by these presents, that the undersigned hereby makes, constitutes and
appoints Karen Maloney, Suzanne Murray and Wendell Taylor as the undersigned?s
true and lawful attorney-in-fact, with full power and authority as hereinafter
described on behalf of and in the name, place and stead of the undersigned 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 (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
filingswith the SEC of reports required by Section 16(a) of the Securities
Exchange Act of 1934 and the rules and regulations promulgated thereunder,
as amended from time to time (the ?Exchange Act?), or any rule or regulation
of the SEC;

(2) prepare, execute, acknowledge, deliver and file Forms 3, 4, and 5
(including any amendments thereto) with respect to the securities of Biogen
Inc., a Delaware corporation (the ?Company?), with the SEC, any national
securities exchanges and the Company, as considered necessary or advisable
under Section 16(a) of the Exchange Act;

(3) seek or obtain, as the undersigned?s representative and on the
undersigned?s behalf, information on transactions in the Company?s
securities from any third party, including brokers, employee benefit
plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to the undersigned and
approves and ratifies any such release of information; and

(4) perform any and all other acts which in the discretion of such
attorney-in-fact are necessary or desirable for and on behalf of the
undersigned in connection with the foregoing.

The undersigned acknowledges that:

(A) this Limited Power of Attorney authorizes, but does not require,
such attorney-in-fact to act in their discretion on information provided
to such attorney-in-fact without independent verification of such
information;

(B) any documents prepared and/or executed by such attorney-in-fact
on behalf of the undersigned pursuant to this Limited Power of Attorney
will be in such form and will contain such information and disclosure
as such attorney-in-fact, in his or her discretion, deems necessary
or desirable;

(C) neither the Company nor such attorney-in-fact assumes (i) any
liability for the undersigned?s responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned
for any failure to comply with such requirements, or (iii) any obligation
or liability of the undersigned for profit disgorgement under
Section 16(b) of the Exchange Act; and

(D) this Limited Power of Attorney does not relieve the undersigned
from responsibility for compliance with the undersigned?s obligations
under the Exchange Act, including without limitation the reporting
requirements under Section 16 of the Exchange Act.

The undersigned hereby gives and grants the foregoing attorney-in-fact
full power and authority to do and perform all and every act and thing
whatsoever requisite, necessary or appropriate to be done in and about
the foregoing matters as fully to all intents and purposes as the
undersigned might or could do if present, hereby ratifying all that such
attorney-in-fact of, for and on behalf of the undersigned, shall lawfully
do or cause to be done by virtue of this Limited Power of Attorney.

This Limited Power of Attorney shall remain in full force and effect
until revoked by the undersigned in a signed writing delivered to such
attorney-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Limited Power of
Attorney to be executed as of this 11th day of February 2021.





                                         	/s/ Michael McDonnell
						Signature
     						Name:  Michael McDonnell