The 34-year-old former world No. 1, who hasn't played Davis Cup since 2000, will compete when the United States meets Croatia in an opening-round match in Carson, Calif., March 4-6.
Agassi cut back his schedule in 2000 to concentrate the majority of his tournament preparation on the Grand Slams. He was a member of three Davis Cup championship teams (1990, 1992, 1995). He has a 30-5 overall singles record for the event.
McEnroe's team will include Agassi, Andy Roddick and brothers Bob and Mike Bryan when the United States plays the Croatians.