The Baby hitmaker teased his Instagram.com followers early on Wednesday (02Apr14) by posting a photo of himself posing with Mahone and his pal's Cash Money Records boss Bryan 'Birdman' Williams and rapper MACk Maine.
Alongside the snap, he simply wrote, "New music", while Mahone was more forthcoming with his photo upload, captioning the shot, "What an amazing song last night..The world isn't ready! @justinbieber."
A source tells GossipCop.com, "Justin knew Austin has been in the studio working on his album and had a song he thought could be really perfect to do with Austin."
Mahone, who has long drawn comparisons to Bieber, was signed to a joint deal between Universal and Lil Wayne's label Young Money Entertainment and Birdman's Cash Money Records last year (13).
Bieber, who is also a Universal artist, previously recorded his 2012 hit Beauty and a Beat with another Young Money/Cash Money artist, Nicki Minaj.