The incident happened just before 1 a.m. at the intersection of East New York Avenue and Rockaway Parkway in Crown Heights.
Responding officers discovered the 25-year-old victim unconscious and unresponsive.
He was rushed to Kings County Hospital where he was pronounced dead on arrival.
The preliminary investigation determined that the victim was traveling southbound on Rockaway Parkway when he struck the rear of an MTA bus that was traveling east on East New York Avenue.
The identity of the male is pending proper family notification, and the investigation is ongoing.