Justin Bieber and Selena Gomez are far from breaking up ... the teen heartthrobs spent the night together AGAIN last night, after a quiet night in on Friday, the two pop stars hit the recording studio Saturday night to get some work done.

Some other famous voices joined Selena in the studio ... but we'll tell you more about that later ...

Bieber joined Gomez at Conway Studios around 10pm and they stayed until midnight before leaving in Justin's van, back to the Four Seasons Hotel, where he's been staying (when he's not sleeping over at Selena's house).

We got a single snap of Selena as she made her way into the hotel, but Bieber was playing hard to get :)