Bieber, who dated Gomez on and off since 2010 and rekindled their romance a year ago before eventually calling it quits for good in March, originally got the tattoo in 2013, when he and Gomez were still head over heels for one another.
Bieber, 24, commented on a photo of Baldwin, 21, on her page saying: "Dats mine".
"This is my ex-girlfriend, so I kinda tried to cover her face up with some shading", he said at the time.
The pal revealed: "One thing he loves about Hailey is that she is so open and not scared of anything and is very independent". "Justin is no longer a topic of conversation in her life".
Bieber's post says he was planning to wait on an announcement but "word travels fast".
Justin told everyone that he would always love Selena as she was his first love. "So committed to spending my life getting to know every single part of you, loving you patiently and kindly".
Selena, who spent the day the engagement news first made headlines living her best life with friends on a super-yacht, has since been spotted wearing her heart on her sleeve - or more accurately, her tee. You make me so much better and we compliment eachother so well! This will be it for him, else Jesus will get angry and I'm sure he doesn't want that.
Apart from Gomez and now Baldwin, Bieber has been romantically linked with many other famous young women such as models Sofia Richie and Ashley Moore.