Chapman, who joins Jack Nicklaus, Gary Player and Hale Irwin as the only players to win the US Senior Open and the Senior PGA Championship in the same year, fired a four-under round of 66 to finish 10 under.
The Englishman won the Senior PGA Championship by the same margin two months ago.
"It's a true honour," Chapman said.
Bernhard Langer, Fred Funk, Tom Lehman and Corey Pavin all finished on eight-under 77 to score them second overall.


