The rapper ecstatically announced Wednesday his Philly fashion designer GF, Milano Harris, gave birth to their first child together. Meek said, "Milano dropped me off a king on my birthday! #thebestgift ❤️."

No word yet on the new kid's name ... but that hasn't stopped Milano from celebrating their new arrival. She's been flooded with congrats on social media ... after months of posting pics of her growing belly.

She first revealed the pregnancy back in December at her Milano Di Rogue fashion show, saying ... "Im a creative, so I didn’t want to announce my pregnancy to the world or even to my family with just a photo of my baby bump. I wanted to create a moment that I could cherish and remember forever. We planned this show in 6 weeks and I have to say this was the hardest show we’ve planned to date but all in all I’m so happy with the turn out."

Meek and Milano have been dating for about a year now. Back in February during his Twitter spat with ex Nicki Minaj, Meek confirmed he was expecting a kid with Milano in a since-deleted tweet that said, "My girl is pregnant watching me tweet about my ex is very clownish ... Ima exit."

This will be Meek's third son. He has 2 sons from a previous relationship.

CONGRATS!!!