Justin Bieber's Triumphant Return on Stage ... Kanye, Kris, Hailey Cheer Him On (VIDEO)

Justin Bieber got on stage Saturday night ... a big deal because it's his first full concert performance in 2 years ... and guess who closed the show?

Justin took the stage Saturday at KIIS FM's Wango Tango, 2015 in Carson, CA. Fans went crazy for 4 hours before Bieber took the stage at 8:30 PM.

Kanye closed the show, so it wasn't surprising his mother-in-law Kris Jenner was in the audience. A little surprising ... she was sitting next to Big Sean, who had beef with Bieber over the whole Ariana Grande hugging thing.