Hailey Baldwin and Justin Bieber. Picture: Supplied

Justin Bieber's mother has hailed Hailey Baldwin as "a daughter" to her, as the model celebrated her 22nd birthday.

Pattie Mallette took to Twitter on Thursday to wish Hailey a happy birthday, and said she's pleased to have her as part of the family after she tied the knot with 'Sorry' hitmaker Justin in a secret ceremony in September.

Posting a message to Hailey - who celebrated her 22nd birthday on the same day as the American holiday Thanksgiving - on social media, Pattie wrote: "HAPPY BIRTHDAY @haileybaldwin !! I LOVE YOU!! I'm SO #THANKFUL to have you as a daughter!!! (sic)"

The tweet was accompanied by several emojis, including hearts, clapping hands, party streamers, a maple leaf - which is synonymous to Canada, where Justin and his family hail from - and smiley faces.

And the sweet post comes after Hailey recently changed her social media profiles to show off her new last name.

The model's Instagram name now reads Hailey Rhode Bieber, whilst her username has changed from @haileybaldwin to @haileybieber.

Meanwhile, Justin, 24, and Hailey are said to be spending Thanksgiving with Justin's father Jeremy Bieber, despite his Canadian roots meaning he didn't grow up with the American tradition.

A source said: "Justin didn't grow up celebrating Thanksgiving, but they are doing a dinner tomorrow night."

Justin also recently dialled back his work commitments in order to spend more time with his new wife, and sources say he's "content" with where his life is now.

An insider said: "He's happy and content. He is in love with Hailey. She encourages him to do whatever he wants to do, and is encouraging him in this season of self-discovery ... It actually bugs him when people ask when he's going back to the studio or on tour. He has worked for years, and the first time he takes a significant break, everyone's all, 'When's he coming back?' To Justin, those aren't just questions - those are demands. For years, everyone has tried to take a piece of him. Just let him be.