The bout was announced during Tuesday night’s edition of UFC Tonight.
Henderson (19-2) lost his final WEC bout before entering the Octagon, but has done nothing but win since making the jump to the UFC.
He has currently won seven consecutive fights, including four title bouts.
Henderson took the belt from Frankie Edgar at UFC 144, defended it against him in an immediate rematch, then defeated Nate Diaz and Gilbert Melendez.
Grant (21-5) more than earned his shot at the champion when he put a punctuation mark on his current five-fight winning streak by knocking out out Gray Maynard at UFC 160 at the end of May.
“We’re looking at all these different fights and options and all these different things to do. I wanted to make sure that the next contender for the title was putting on great fights,” UFC president Dana White said following UFC 160. “I wanted to see something good tonight, I wanted to see something special, and I saw that tonight. Grant’s getting the next title shot.”
Benson Henderson vs. TJ Grant headlines on Aug. 31 at the HMO Harris Bradley Center in Milwaukee.