Tim Tebow's officially a dad ... his wife, Demi-Leigh, just revealed she gave birth to the couple's first child over the weekend.

Demi-Leigh said on her Instagram page the bundle of joy entered the world on Sunday ... and Mom, Dad and little girl are all happy and healthy.

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"Our daughter is here!" Demi-Leigh wrote on her IG. "We couldn't be more grateful for the blessing and gift of this new little life."

"We’re so grateful to the whole medical team that assisted us in the best way possible during my labor and delivery. From our doctor to our nurses and all the hospital staff — we are so grateful and thankful for you."

She added, "Thank you to everyone who’s been praying with us over her arrival. We are so incredibly thankful for all of the love and support we’ve felt."

Demi-Leigh included a whole bunch of pictures from her hospital room, and in almost all of them, Tim couldn't have appeared happier.

He was seen with a smile on his face multiple times -- and in another, he was spotted giving a loving kiss to Demi-Leigh.

No word yet on the baby's name -- Demi-Leigh promised that's coming "soon."

Congrats!!!