Canseco announced the date Saturday on his Facebook page.
The venue has not been announced. Promoter is Damon Feldman, who's been behind similar exhibitions.
Simmons, who's 47, 6-foot-5 and 330 pounds, acknowledges that he's getting into the ring for the money and the exposure. He is working on a brand of chicken wings that will hit grocery stores in August.
Canseco, who's 44, 6-foot-3 and 250 pounds, is fresh off a defeat in his mixed martial arts debut. Last month, 7-foot-2 sumo wrestler/kick boxer Hong Man Choi whupped him in 77 seconds in Japan. In previous appearances in the Philly area, Canseco boxed WYSP morning man Danny Bonaduce to a draw in January and lost to NBC10 sports director Vai Sikahema in July 2008.
Simmons, who says he's a street fighter, boxed a pro wrestler named Smoke to a draw in 2003.