Justin Bieber Triumphant Return on Stage Kanye, Kris, Hailey Cheer Him On

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.

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And Hailey Baldwin was also cheering Justin on ... there's a buzz the 2 have been dating.