At the time of this writing, no further details about Miller's death have been released to the public.
Last month, Miller released his fifth studio album "Swimming" and was scheduled to begin his USA tour in October.
Mac started: "I just wanna go on tour", which was quickly liked more than 33,000 times and retweeted to thousands.
Miller had long struggled with substance abuse issues.
Ed Sheeran, Post Malone, Solange, Chance The Rapper, Travis Barker and Snoop Dogg are just some of Mac's peers to share their thoughts, while here in Australia, artists such as Cub Sport and Alison Wonderland have also paid tribute (read what they all had to say below).
An investigation into Mac's death is underway, authorities have said.
In 2014, it was reported that Mac had signed a deal for himself and his label with Warner Bros Records. Great man. I loved him for real.
Ariana and Mac seemed inseparable during their romantic relationship that lasted two years.
"I really wouldn't want just happiness", he said during an interview that took place last month but was published on Thursday. Would I rather that no one said anything and life just moved on normally?
"At his record release in NY he was happy taking pictures, we felt like he was back".
"He was one of the sweetest guys I ever knew, "the rapper wrote on Twitter".
However, and despite Miller's historic battles with addiction, Ms Grande and her new partner have been at the receiving end of huge amounts of online abuse since the death was announced by TMZ on Friday.
This week, Grande performed her first United Kingdom show since the One Love Manchester benefit concert a year ago, playing an intimate set at London's KOKO.