Rousey revealed the birth on her Instagram page late Monday evening ... saying in the caption, "La’akea Makalapuaokalanipō Browne❤️."

The two pics Rousey shared to bring the good news to her fans were adorable, with one featuring the baby's hand over Ronda's heart and the other showing the baby's hand on the chest of her hubby, Travis Browne.

The child is Browne and Rousey's first ... and it's clearly safe to assume they're pumped over the birth -- given how excited they've been throughout the whole babymaking process.

You'll recall, 34-year-old Rousey left the WWE in 2019 to try to start a family with Browne ... and back in April, she and Travis shared the good news of their pregnancy.

Just a few months later, the couple also revealed the gender of the baby with a funny Pokemon-themed vid.

No word yet if the birth means Rousey is one step closer to making a WWE comeback -- but we're betting she'll be pretty content being Mom for now.