The 24-year-old singer and the blonde beauty only rekindled their romance last month after having previously dated in 2016, but according to two eyewitnesses, the pair are now set to tie the knot.
Two women told TMZ.com that they saw the proposal take place and claim it happened at a resort in the Bahamas.
They told the publication: “Everyone was at a restaurant on the property doing salsa dancing when Justin's security told everyone to put their phones away, because something special was about to happen.”
The women claim the ‘Love Yourself’ hitmaker then got down on one knee and asked Hailey, 21, to marry him.
Another source told TMZ that Justin and Hailey got engaged on Saturday night.
Justin’s dad, Jeremy Bieber, has seemingly confirmed the news as he took to Instagram on Sunday to congratulate his son on his “next chapter”.
Posting a picture of the ‘Sorry’ singer, Jeremy wrote: "@justinbieber Proud is an understatement! Excited for the next chapter! (sic)”
Hailey's father Stephen Baldwin appears to have confirmed the reports.
The actor tweeted this evening: "Sweet smile on my face! me&wife (Kennya) Always pray 4 Gods will!!
"He is moving in the hearts of JB&HB. Let's all pray for His will to be done.
"Love you 2 so much!!! #Godstiming #bestisyettocome."
He also tagged Bieber's parents Jeremy Bieber and Pattie Mallette and wrote "Congrats".
The news comes after the on again off again couple were seen making sundaes in Sag Harbour last weekend, before being spotted locked in a "passionate make-out session”.
A source said: "Justin and Hailey have always been into one another. They dated in 2016 briefly, and the feelings never really went away.
"Justin and Hailey have been casually dating for roughly a month, but things seem to be heating up as the two are spending more and more time together.”
And last month, Hailey revealed she and Justin had "moved past" the "weirdness" of their split.
She said: "Justin and I were friends for a long time. I met him when I was really young and he was one of my best friends. Everybody knows that at a certain point in time that turned into something else, but that just happens when you're 18, 19. It was what it was.
"We went through a long period of time when we weren't friends. We didn't speak for quite some time and there was a lot of weirdness that went on.
"We've moved past that. I'd never been through [a high-profile relationship] like that. But it brought both of us to the realisation that we just work much better as friends. He's somebody I really cherish. Now it's a very mature situation. It's good."