Clijsters will make her WTT debut July 21 in St. Louis and play in Philadelphia on July 22.
The former No. 1 player retired from the WTA Tour in May 2007. She gave birth to a daughter last year.
Andre Agassi, Venus and Serena Williams and John McEnroe are among the players who will compete in the league, which runs from July 2-26 in 10 cities.