Exhibit 10.23

AMENDMENT NO. 2 TO EMPLOYMENT AGREEMENT

This AMENDMENT NO. 2 TO EMPLOYMENT AGREEMENT is entered into on the 31st day of
December, 2009, is between COMCAST CORPORATION, a Pennsylvania corporation
(together with its subsidiaries, the “Company”), and BRIAN L. ROBERTS
(“Employee”).

BACKGROUND

WHEREAS, the parties entered into an Employment Agreement dated as of January 1,
2005, as amended by Amendment to Employee Agreement dated as of February 13,
2009 (together, the “Agreement”), that sets forth the terms and conditions of
Employee’s employment with the Company, and

WHEREAS, the parties desire to amend the Agreement on the terms and conditions
contained herein.

NOW, THEREFORE, the parties hereto, intending to be legally bound hereby, agree
as follows:

1. Subparagraph 5(b) of the Agreement is hereby amended to add the following
year and amount thereto: “Year – 2010; Amount – $3,000,000.” 2. Except as
modified hereby, the Agreement shall continue unmodified and in full force and
effect.

IN WITNESS WHEREOF, the parties hereto have executed and delivered this Second
Amendment on the date first-above written.

 

COMCAST CORPORATION By:   /s/ Arthur R. Block EMPLOYEE: /s/ Brian L. Roberts
Brian L. Roberts