Kevin Hart -- Yup, I Was Drunk

Kevin Hart was not under oath, but he still told the truth to TMZ on his way out of jail ... he was drunk when cops busted him for DUI.

As TMZ first reported, Hart was popped for suspicion of DUI early Sunday morning after California Highway Patrol officers spotted him speeding and driving erratically on the freeway.

On his way out of jail this morning, Hart fully admitted to being drunk ... and even said he told the officers as much. Guess he doesn't plan on pleading not guilty.