<PAGE>
                                                                      EXHIBIT 24

                               POWER OF ATTORNEY

    KNOW ALL MEN BY THESE PRESENTS:

    WHEREAS, MediaOne Group, Inc., a Delaware corporation (hereinafter referred
to as the "Company"), proposes to file with the Securities and Exchange
Commission, under the provisions of the Securities Exchange Act of 1934, as
amended, an annual report on Form 10-K for the fiscal year ended December 31,
1999; and

    WHEREAS, each of the undersigned is a Director of the Company;

    NOW THEREFORE, each of the undersigned constitutes and appoints RICHARD A.
POST and STEPHEN E. BRILZ, and each of them, as attorneys for him or her and in
his or her name, place, and stead, and in his or her capacity as a Director of
the Company, to execute and file such annual report, and thereafter to execute
and file any amendment or amendments thereto on Form 10-K, hereby giving and
granting to said attorneys full power and authority to do and perform all and
every act and thing whatsoever requisite and necessary to be done in and about
the premises as fully, to all intents and purposes, as he or she might or could
do if personally present at the doing thereof, hereby ratifying and confirming
all that said attorneys may or shall lawfully do, or cause to be done, by virtue
hereof.

    IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney this 8th day of March 2000.

<TABLE>
<S>                                                         <C>
                /s/ KATHLEEN A. COTE                                        /s/ CHARLES M. LILLIS
     -------------------------------------------                 -------------------------------------------
                  Kathleen A. Cote                                            Charles M. Lillis

               /s/ ROBERT L. CRANDALL                                     /s/ CHARLES P. RUSS, III
     -------------------------------------------                 -------------------------------------------
                 Robert L. Crandall                                         Charles P. Russ, III

                  /s/ GRANT A. DOVE                                         /s/ LOUIS A. SIMPSON
     -------------------------------------------                 -------------------------------------------
                    Grant A. Dove                                             Louis A. Simpson

                /s/ ALLEN D. GILMOUR                                           /s/ JACK SLEVIN
     -------------------------------------------                 -------------------------------------------
                  Allan D. Gilmour                                               Jack Slevin

                /s/ PIERSON M. GRIEVE                                      /s/ DANIEL W. YOHANNES
     -------------------------------------------                 -------------------------------------------
                  Pierson M. Grieve                                          Daniel W. Yohannes
</TABLE>

<PAGE>
                               POWER OF ATTORNEY

    KNOW ALL MEN BY THESE PRESENTS:

    WHEREAS, MediaOne Group, Inc., a Delaware corporation (hereinafter referred
to as the "Company"), proposes to file with the Securities and Exchange
Commission, under the provisions of the Securities Exchange Act of 1934, as
amended, an annual report on Form 10-K for the fiscal year ended December 31,
1999 and

    WHEREAS, the undersigned is an officer or Director, or both, of the Company
and holds the office, or offices, in the Company as indicated below his name;

    NOW THEREFORE, the undersigned hereby constitutes and appoints RICHARD A.
POST and STEPHEN E. BRILZ, and each of them, as attorneys for him and in his
name, place, and stead, and in each of his offices and capacities in the
Company, to execute and file such annual report, and thereafter to execute and
file any amendment or amendments thereto on Form 10-K, hereby giving and
granting to said attorneys full power and authority to do and perform all and
every act and thing whatsoever requisite and necessary to be done in and about
the premises as fully, to all intents and purposes, as he might or could do if
personally present at the doing thereof, hereby ratifying and confirming all
that said attorneys may or shall lawfully do, or cause to be done, by virtue
hereof.

    IN WITNESS WHEREOF, the undersigned has executed this Power of Attorney this
8th day of March, 2000.

                                                  /s/ CHARLES M. LILLIS

                                          --------------------------------------
                                                    Charles M. Lillis
                                           CHAIRMAN OF THE BOARD, PRESIDENT AND
                                                 CHIEF EXECUTIVE OFFICER