Jennifer Hudson Brings Down House at Jamie Foxx Birthday

Jamie Foxx may have been the guest of honor at his 48th birthday party ... but it was Jennifer Hudson who stole the show.

We're told Jamie's friends threw a surprise bash for him at Le Bilboquet in NYC Saturday night -- and of course, there was major star power, including Alicia Keys and rumored GF Katie Holmes.

But it was his "Dreamgirls" costar, Jennifer Hudson, belting out, "And I Am Telling You," that was the best moment of the party.

Check out the video ... it's safe to say J Hud slayed.