"We've known Zak for a while and we asked him if he'd play on a few songs and he said yeah, and he has done and it's been absolutely fantastic," Gallagher said.
Gallagher did not confirm, or deny, that Starkey would have a permanent spot in the band.
"If he can get us his dad's autograph he's in," Gallagher said.
Starkey previously has played with The Lightning Seeds and The Who.
The Glastonbury Festival takes place at Worthy Farm, Pilton, Somerset, June 25-27. Paul McCartney and Muse also have been confirmed at the event.