Antonio Brown got real cozy with Lil Kim at a party over the weekend ... putting his face on her breast, grabbing a handful of her butt -- and even at one point kissin' her on the lips!!
The twosome's steamy night out all happened on Saturday at a swanky New York yacht bash -- thrown by celebrity music manager Big Fendi.
You can see in a video from the dance floor posted to Brown's Instagram page on Wednesday ... Lil Kim hopped on the mic to entertain partygoers -- when Brown suddenly got super handsy with her.
Check out the footage ... Brown appeared to kiss one of her boobs -- all while he caressed her ass. Kim seemed to love it -- so much so, that later in the night, the two were spotted smoochin'.
It appears they hung out for most of the evening together even when Kim wasn't on the microphone ... in another video Brown posted to his IG, you can see they sat next to each other in what looked like a VIP section.
No word at all if this was just a one-night thing or the start of a high-profile romance ... but either way, what a party!