Robin Thicke was caught with a fattie.

The R&B singer-songwriter was busted in Manhattan for marijuana possession yesterday after he was allegedly spotted smoking a joint in an SUV.

Cops smelled pot and saw Thicke, 34, toking up in the rear seat of a Cadillac Escalade at 12:25 p.m. on Third Avenue near East 21st Street, authorities said.

He was released after being issued a desk-appearance ticket.