Justin Bieber Unplugged for Image Rehab [TMZ TV]

1/21/2015 6:00 PM PST

Justin Bieber -- Unplugged for Image Rehab (TMZ TV)

TMZ TV

Justin Bieber did an impromptu acoustic concert in L.A. ... and sounded great -- further proving he's making big changes in his life and his career. He didn't even pee in a bucket during the gig!

Hard to believe, but it's looking like bad boy Biebs is gone for good.