Gerald Pender, 60, was going eastbound when he crossed North Ocean Avenue and was hit by a Honda Civic going south on North Ocean, police said.
Pender was taken to Stony Brook University Medical Center, where he was pronounced dead, police said.
The accident happened about 6:30 p.m. and led to the closure of the westbound service road and the Exit 63 off ramp to North Ocean Avenue, authorities said. North Ocean was also shut down between the north and south service roads, they said.
The roads reopened about 9:30 p.m.
The Honda driver, Sean Dwyer, 29, of Patchogue, was not injured.
The car was impounded for a safety check.
Detectives ask anyone with information to call 631-854-8652 or anonymously to Crime Stoppers at 800-220-TIPS.