The Portuguese replaces Jose Mourinho, who was sacked way back on April 19, bringing an end to a chaotic recruitment process.
He has penned a two-year deal at the north London club.
The 47-year-old said: “When you have a squad with quality and talent, we want to make the fans proud and enjoy.
“It’s an enormous pleasure and honour (to be here), there’s joy and I’m happy and looking forward to starting work.
“We don’t have any days to lose and we must start working immediately as pre-season starts in a few days.”