The two were spotted out and about in Miami over the weekend while attending the VOUS conference, adding more fuel to speculations that they've recently reignited their romance.
Bieber, 24, and Baldwin, 21 -- who briefly dated in 2015 -- spent Sunday together, kicking off their night with dinner at Casa Tua. They then went to club LIV in Miami Beach around 1 a.m., spending most of their time in one of the club's sky boxes, according to an eyewitness.
The model dressed to impress for the outing, rocking a white slip dress with Adidas kicks and stunning statement jewelry. Bieber opted for a more casual ensemble, consisting of a black-and-white hoodie and plaid pants.
Inside the club, it appears Bieber and Baldwin weren't shy about getting close with one another. A fan captured the "Sorry" singer at one point putting his arm around the blond beauty, posting the video to Instagram on Monday.
An eyewitness tells ET that they left the club together around 3:20 a.m., holding hands and hopping into a black Escalade.
They were also spotted together the next morning, cuddling up close on a balcony.
The latest outing comes just two days after Bieber and Baldwin were seen together at the Living Room inside the W South Beach. According to an additional eyewitness, they appeared to be having a low-key night, enjoying drinks with friends. The eyewitness also tells ET that they sat very close together, held hands and stole an occasional kiss every now and then.
Justin’s group appeared to be super sweet and respectful of the staff serving them.
"Justin and I were friends for a long time," she revealed. "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," she continued. "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 realization that we just work much better as friends. He's somebody I really cherish. Now it's a very mature situation. It's good."