Post Malone got a SECOND lease on life in the early hours of Friday morning … after walking away unscathed after a scary car crash.

Law enforcement sources tell TMZ … the rapper was a passenger in his Rolls-Royce Friday in WeHo at 2:40 AM when a Kia T-boned the Rolls on the driver’s side.

Moments after the crash, Post told us the Kia hit them out of nowhere … causing the Rolls-Royce to spin out of control. Photos back up his version.