Rebel Wilson surprised fans Monday with news she has welcomed a baby girl via surrogacy.

Wilson, 42, shared a photo of her daughter on Instagram.

"Beyond proud to announce the birth of my first child, Royce Lillian, born this past week via surrogate," Wilson revealed in the post.

"I can't even describe the love I have for her, she's a beautiful miracle! I am forever grateful to everyone who has been involved, (you know who you are), this has been years in the making…but particularly wanted to thank my gorgeous surrogate who carried her and birthed her with such grace and care. Thank you for helping me start my own family, it's an amazing gift. The BEST gift!!"

Rebel Wilson welcomes a baby girl

Rebel Wilson announced she welcomed a baby girl via surrogate. (Instagram: Rebel Wilson)

REBEL WILSON SHOOTS DOWN ENGAGEMENT RUMORS TO GIRLFRIEND RAMONA AGRUMA

She added: "I am ready to give little Roycie all the love imaginable. I am learning quickly…much respect to all the Mums out there! Proud to be in your club."

The "Pitch Perfect" star revealed her decision to embark on a "year of health" came after her fertility doctor noted she'd have a better chance at becoming a mom if she made some changes.

"He looked me up and down and said, 'You'd do much better if you were healthier,'" the actress told People magazine.

"I was taken aback. I thought, 'Oh God, this guy's so rude.' He was right. I was carrying around a lot of excess weight. It's almost like I didn't think of my own needs. I thought of a future child's needs that really inspired me to get healthier."

Rebel Wilson and her girlfriend Ramona Agruma smile for a picture at the Operation Smile's 10th Annual Park City Ski Challenge

Rebel Wilson recently shot down engagement rumors to her girlfriend Ramona Agruma in an Instagram story. (Alex Goodlett/Getty Images for Operation Smile)

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The actresses ended up losing 80 pounds.

Recently, Wilson shot down reports that she was engaged to her girlfriend Ramona Agruma.

In a video shared to her Instagram story, the couple posed in front of Cinderella's Castle at Disneyland, displaying a united front. The caption read, "Thanks for the well wishes, but we are NOT engaged."

Page Six had previously reported that the women had been discussing their engagement at a recent Halloween party.

Rebel Wilson and her girlfriend Ramona Agruma both show up to the U.S. Open in jeans, baseball hats, and sunglasses

Rebel Wilson and Ramona Agruma have been dating for several months, with the Australian actress going public with the relationship in June. (Jean Catuffe/GC Images via Getty Images)

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Wilson went public with her relationship with Agruma in June, sharing in an Instagram post, "I thought I was searching for a Disney Prince … but maybe what I really needed all this time was a Disney Princess."

The two were set up through a mutual friend, according to the actress.

In May, Wilson shared in an interview with People Magazine that her relationship with Agruma (who she didn't name at the time) blossomed in an "old-school" way. They talked on the phone for several weeks before ever going on a date, but Wilson noted it was a "really good way to get to know each other."

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Fox News Digital's Caroline Thayer contributed to this report.