Organizers say Mickelson will join Tiger Woods to play in the event scheduled for Sept. 4-7 at TPC Boston in suburban Norton.
Mickelson has played only three tournaments since the U.S. Open in June after taking time off to be with his wife, Amy, and his mother, Mary, who were both recently diagnosed with breast cancer.
Mickelson has won twice this season and has six top-10 finishes in 14 events.
This year’s championship features a record $7.5 million purse and a $1.35 million winner’s check. The top 100 players in the FedEx Cup points standings qualify for the event. Mickelson is ranked sixth, with 1,630 points.