The solo star will be joined by Beck and US alt-rockers The National at the summer bash. The former Smiths frontman has claimed he is "honoured" to be playing the event.
Speaking about the show, Morrissey said: "I am honoured to be asked to headline on July 4th, marking my 26th year haunting British music, and following the Hyde Park greats - T.Rex, Joan Armatrading, and someone with insecure teeth.
"I promise a thundering bill of tight nerves and suavity and all your favourites from Disc magazine. I will take Hyde Park like a flea inhabits a dog.
"Art-hounds and people with badly cut hair are very welcome. I shall do my utmost not to pull a sour face. The sun will make up its own mind."
Early bird tickets go on sale this Friday. O2 Wireless runs from July 3-6. Saturday and Sunday's lineups have already been announced.
Fatboy Slim will be joined by Sam Sparro, The Whip, Robyn and Mark Ronson on the Saturday.
Counting Crows will play with the Goo Goo Dolls, Powderfinger, The Hold Steady and Bowling For Soup on the Sunday.