The former Oasis frontman, 48, headlined Friday night of the music event with a set including the hits Live Forever, Supersonic and Roll With It.
On Saturday afternoon, he tweeted a picture of himself with a plaster covering his nose and ointment applied to a number of cuts.
Gallagher compared himself to the late The Who drummer Keith Moon, who was infamous for his wild behaviour.
The singer tweeted: “So check this out I fell out the helicopter last night you couldn’t rite it all good who said RnR is dead Keith moon eat your drum skin out C’mon you know LG x”
Gallagher jokingly responded to one fan who asked how high he had fallen from, saying “100 thousand feet”.
Another fan asked if there was any CCTV footage of the fall, prompting him to respond: “Yeah it’s in the nxt video.”
It comes ahead of the release of new documentary, Oasis Knebworth 1996, celebrating the 25th anniversary of the Britpop band playing two concerts at Knebworth Park, Hertfordshire.
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