California Highway Patrol officials say the man was found shortly before 10:30 a.m. on the right shoulder of the southbound onramp.
Authorities confirmed the body was that of a man in his 20s. Though the official cause of death remained undetermined, LAPD officers said they are not ruling out foul play.
The onramp was closed for several hours as investigators tried to figure out the man's identity and what happened to him.
City News Service contributed to this report.