While this may seem like a huge - and very fast - step, the pop star and model have slowly been building their relationship for quite some time now: first dating in 2014, before rekindling in 2016.
Below, their complete relationship timeline.
2011: The First Meeting
If you want to be my lover, you got to get with my friends. Or at least hang out with them. Right? Bieber and Hailey have known each other since they were teens, (Hails just 13 to be exact) but it wasn't until a month after Bieber and Selena Gomez broke up back in late 2014, did rumours of a potential romance between the two begin to spark. Starting with a November 2014 report by Hollywood Life that claimed Hailey was Justin's "new muse."
Whilst, Hailey and Justin both denied the romance, insisting they were just friends, the pair began officially hanging out regularly in the same social group.
February 2015: Still ‘Just Friends’
Hailey told E! at the amfAR New York Gala. “We’re just friends. I’ve known him for a long time, since I was about 13,” “He’s just going through a time in his life where he’s transitioning in a really positive way and he needs good people around him. And I’m trying to be a good friend and be there for him and support him.”
The pair was later photographed leaving New York hotspot Up & Down early one morning in February. Earlier that same day, Hailey told reporters at the Fendi New York flagship store launch that she was single.
December 2015: New Year's Eve PDA
Justin and Hailey grew even closer while celebrating a holiday together in Anguilla. While the two had not commented on the status of their relationship, fans were already going crazy, giving them a couple's nickname 'Jailey.'
A source tells E! News that Justin and Hailey's relationship is "more of a just a fling," adding, "They have a lot of fun together but don't know what will happen now. They aren't thinking too much about it and are just having fun."
January 2016: Insta-Official
Their romance sizzled over the 2016 New Year's holiday when they vacationed in the Caribbean together.
Fast forward to St Bart's New Year's Eve Party 2016, when Bieber and Baldwin finally gave fans a more concrete glimpse into their love life with Beiber's Instagram post that confirmed they were really more than just friends.
August 2016: Justin Says He Might Marry Hailey
After their mysterious breakup in August 2016, JB and Hailey entered a period of no contact. The two were not friends, they didn't see or follow each other on social media. During this period of no contact, Justin Bieber was on-again-off-again with Selena Gomez and rumours of Hailey and Shawn Mendes as at item also spread.
But looking back, perhaps Justin already knew she was the woman he wanted to marry. Speaking to GQ, he said: "I don't want to feel like the girl I love is an added responsibility," he muses. "I know that in the past I've hurt people and said things that I didn't mean to make them happy in the moment. So now I'm just more so looking at the future, making sure I'm not damaging them. What if Hailey ends up being the girl I'm gonna marry, right? If I rush into anything, if I damage her, then it's always gonna be damaged. It's really hard to fix wounds like that. It's so hard.… I just don't want to hurt her."
April 2016: Hailey Speaks Out
"I don't want attention out of dating somebody," she told Marie Claire. "It's hard to date somebody in this industry. You have to have really thick skin and be very strong. You have to focus on the person and nothing else."
June 2018: Reunion In Miami
Romance rumours began to spark again when the couple reunited in Miami and holiday together in the Hamptons. In photos obtained by the Daily Mail, Justin and Hailey were seen cuddling and kissing.
July 2018: Loved-Up
The pair made no secret of their rekindled romance: holding hands in New York and kissing in parks. They then jetted off tho the Bahamas for a vacation.
July 7, 2018: Engaged!
Justin and Hailey got engaged in the Bahamas during dinner at a local restaurant on Saturday night. Bieber’s father Jeremy hinted at the engagement news on Instagram writing, “@justinbieber Proud is an understatement! Excited for the next chapter!” Bieber’s mother, Pattie Mallette, also seemingly referenced her son’s engagement on Twitter Sunday, writing, “Love Love Love Love Love Love Love.” Two days later, Bieber confirmed the news in a lengthy Instagram post calling Baldwin the love of his life.
Congrats to the happy couple!