Grande has been represented by the well-known US talent agent since 2013 while Lovato signed to him in 2019.
It comes a week after reports that Justin Bieber was also parting ways with Braun after 16 years, though representatives on both sides have since denied this.
Meanwhile, Colombian star J Balvin, who signed with Braun in 2019, left in May and is now managed by Roc Nation.
Representatives for Braun have been approached for comment.
Braun is one of the world’s most successful music managers, with clients including David Guetta, Black Eyed Peas, Ava Max, Carly Rae Jepsen and Quavo, according to his website.
Grande has released six albums under Braun’s guidance with all but one of them topping the US Billboard charts.
After the Manchester bombing, which claimed the lives of 22 of her fans, Braun organised the One Love benefit concert that helped raise millions of pounds to support the families of the victims.
Grande has not released an album since 2020’s Positions, and is currently working on the movie adaptation of the Broadway musical Wicked.
Lovato has released two albums since signing with Braun – 2021’s Dancing with the Devil… the Art of Starting Over, and Holy Fvck which came out in 2022.
Though the masters have since changed hands again after a deal with investment firm Shamrock Capital, Swift has continued with a bid to regain ownership of the music by creating new versions of the songs.
She has already recorded new versions (“Taylor’s Versions”) of her previous albums Fearless, Red, and Speak Now.
On the last night of her recent sold-out, six-night run of shows at the SoFi Stadium in California, the singer announced the release date for 1989 (Taylor’s Version) – which will arrive on October 27.