The rapper made the surprise announcement Monday morning on Instagram, posting a photo of herself looking at least 6 months along and adding the caption, "#Preggers."

She posted another photo too from what appears to have been a full-blown Beyonce-style baby bump shoot. No caption for the second pic -- none needed really, the image itself does all the talking.

Our girl is very preggo, and is finally ready to tell the world about it.

It's crazy ... because you'll recall Nicki announced back in September 2019 she was retiring and done with the rap game so she can focus on starting her family. It didn't take long before she got back in the game, but also she also got wifed up!

As we've reported ... Nicki ended up marrying childhood friend Kenneth Petty the following month. It seems their relationship has really prospered over the last few months -- minus their brief beef with Meek Mill.

She dropped even more hints this past May, when answering some fan questions she talked about mad cravings, "nausea and peeing nonstop," and even teased a possible baby bump!

So, with that said, congrats on Baby Barbie, NM ... or Baby Ken. Whatever it ends up being.