Derek Jeter: I'M HAVING A BABY!!!

Derek Jeter's gonna be a dad!!

The Yankees legend's wife, Hannah Jeter, just made the announcement on Derek's website, The Players' Tribune ... saying she's pregnant with a little girl!!

It's the couple's first child. Hannah says Derek has a name picked out but she won't reveal it.

Derek and Hannah were married in July. He's 42. She's 26.

Derek retired from the Yankees back in 2014. Glad he's keeping himself busy!

Congrats!