Sources with direct knowledge tell TMZ ... the "Yacht Club" rapper is father to a baby girl who was born in the last couple weeks in New York City.

We're told Lil Yachty is in the Big Apple right now, where he's spending some time with the child.

It's unclear who the mom is ... to us, anyway. Obviously, Yachty knows, but he has had a few different girlfriends recently. Stay tuned.

We reached out to his reps, but so far ... no word back.