Six years ago, Ambakisye Osayaba made his big move — he quit his part-time city job cleaning Central Park and began playing chess full-time.

Now he earns up to $400 a day, taking on all comers from a 2-by-2-foot fold-out table, chairs and chess board he rolls in a metal shopping granny cart every morning to the southwest strip of Union Square Park.

“It’s the best living I’ve ever made,” said Osayaba, 59, known by the initials T.C., which stand for “teaches chess.”

Osayaba may be the top earner of the dozen players in the park, who have migrated there from Washington Square Park over the last few years because they realized Union Square gets more tourist traffic.

“There’s a reason why he’s called the Bobby Fischer of Union Square,” said one of his regular opponents, Mayer Lasry, 20.

Osayaba charges $3 for a no-wager game. If you want to bet, the winner gets $5. He offers 30-minute lessons for $20. He plays at the park year round, rain or shine.

“People walk by all the time wanting to learn,” said Osayaba. “I tell them, ‘Take a seat’ and before they know it, they’re coming back every day.”

Victor Raso, 28, has been taking lessons from Osayaba five days a week for two years.

“When I first came out I knew the rules but nothing about strategy,” said Raso, a facilities coordinator at the clothing store Express who spends his lunch hour in the park. “I stuck with T.C. because he taught me rather than hustled me.”

The only way to get an appointment with T.C. is to show up at his table. “I threw my phone off the Brooklyn Bridge,” Osayaba said. “You need to give the game your full attention.”

Recently, while playing this reporter (a chess novice), Osayaba dragged his plastic, dog-chewed pieces across the rubber board swiftly, never taking more than a few seconds to make a move. He tapped his fingers while waiting for his opponent’s play.

When it was his turn, he nestled his queen next to a king trapped behind his own pawns. “You should have opened up those pawns,” he said. Osayaba uses his queen and rooks to corner his opponents in 10-minute blitz games. “When he brings his queen out, you’re in trouble,” an onlooker said.

Osayaba claims he once won $600 from a worker at nearby Best Buy. “He came over here like some kind of hot shot, throwing money around,” Osayaba aid. “But I knew he was a fish. He was fresh out of water.”

Over three 20-minute games, the Best Buy chess novice challenged Osayaba to a $100 match, then $300, until finally upping the ante to $600.

“I beat the beak off him. I was hitting him with moves I teach my beginners — like the Queen’s Gambit,” he said.

His highest-profile opponent was American grandmaster Hikaru Nakamura’s girlfriend, Maria De Rosa, who is also a highly ranked champion in Italy.

“Nakamura was acting like a jerk, so I asked her to play instead,” Osayaba said. They played informally at the World Chess Championships last year at South Street Seaport.

Osayaba won the game with the help of the late William Lombardy. “He was singing the moves at me while I played her. So technically, Lombardy beat her,” Osayaba admitted.

Lombardy trained Fischer from the time he was 11 years old through his historic 1972 victory over Boris Spassky.

Lombardy, who died Oct. 13, also taught Osayaba.

“He used to hang out here with us all the time,” he said. “In the summer he’d even sleep out here with us when we’d play all night.”

Osayaba was 10 years old in 1968 when he got a chess set for Christmas. “It was a cheap, plastic set, but I loved it,” said Osayaba, who grew up poor with 17 siblings in a tiny Harlem apartment. He would spend hours after school every day studying strategy with a local librarian. “I was infatuated with being the best,” he said. “And I never stopped.”