The Swiss world number three, 31, won last year's final with a four-set victory over Andy Murray.
"I'm just happy to be here and happy to be defending the title as of now," Federer, who is gunning for an eighth triumph at SW19, told Sky Sports News.
"I know the road is hard, but it is possible. I'm looking forward to the challenge."
Federer takes on Romanian world number 47 Victor Hanescu in the first round on Monday.