NBA's John Wall -- Gets $20k Portrait From Famed Street Artist

John Wall had a pretty great birthday party last night -- with celebs, and cake and a $20,000 portrait from a famous street artist, TMZ Sports has learned.

Wall -- who turns 25 on Sunday -- hit up Koi in West Hollywood for a bday bash thrown by Haute Time Magazine. Party organizers tell us guests included several billionaires, top Google execs and NBA superfan Jimmy Goldstein.

But the highlight was the gift -- a custom John Wall portrait painted by Madsteez ... one of the top street artists in the world. We're told the piece cost $20k to commission.

Wall also got a custom $8,000 suit from designer David August and a $2,500 Ulysses Nardin barometer.