The man was in the lanes of travel on eastbound Sunrise Highway (Route 27) in Sayville, east of exit 49, when he was struck by a 2006 Jeep Liberty at about 2:40 a.m. on Thursday, Aug. 19, the Suffolk County Police said.
The victim, now identified as Matthew Wenk, of Islip Terrace was pronounced dead at the scene.
The Farmingville man who was driving the Jeep, also age 20, was not injured in the crash, police said.
Authorities said the vehicle was impounded for a safety check.
Anyone with information on the crash is asked to contact police at 631-854-8552.
Click here to follow Daily Voice Brentwood and receive free news updates.