De Blasio was forced to sing the West Coast anthem -- which includes the lyrics, "hate New York City...all the people dressed like monkeys" -- when he lost his Stanley Cup bet to Los Angeles Mayor Eric Garcetti.
"I always wanted to meet you, but not like this, man!" de Blasio, wearing an "I Heart L.A." t-shirt, told Kimmel, before launching into the song with a group of kids from New York City's 52nd Street Project.
Here's Randy Newman's original version of the song:
Swim Week Miami Beach 2014 [PHOTOS]