Born Malcolm James McCormick and previously known as EZ Mac, Miller was reportedly suffering from drug-related illnesses and substance abuse, especially in light of his break-up with Grande after nearly a two-year-long relationship.
"Although the two ended their relationship, Ariana always shared a deep connection with Mac and wanted nothing but the best for him".
Ariana hasn't spoken out about the tragedy but sources from ET say she is devastated by the loss. "When I first started, I thought I was going to be the biggest thing in the world", Miller told the entertainment site.
"Of course I didn't share how hard or scary it was while it was happening but it was".
The rapper, whose most popular songs included "Loud", "Smile Back" and a collaboration with Grande called "The Way", released his latest album "Swimming" this summer.
The exact cause of his death is yet to be confirmed by the police. It didn't. Instead, over the next seven years, the 26-year-old - real name Malcolm James McCormick, son of a middle class Jewish photographer and architect - took a dogged approach to pushing his sound and message to new brinks of sonic experimentation and lyrical neurosis-busting.
In his recent Instagram post, Mac posted a video of a record player with his song So it Goes playing, with the lyrics: "Nine lives, never die, f**k a heaven, I'm still getting high". His tour to support the album was set to begin in October.
Days after the breakup, Miller was arrested on DUI and hit and run charges after he "allegedly crashed his Mercedes SUV into a power pole near his LA home and fled the scene", according to Rolling Stone.
"I really wouldn't want just happiness", he said during an interview that took place last month but was published on Thursday.
After his 2011 debut "Blue Side Park" was released by an independent label and topped the charts, Miller turned to jazz and funk influences on later albums. "Now I have space for me", he said.
"He was one of the sweetest guys I ever knew, "the rapper wrote on Twitter". "God knows, I came close - don't try this at home".