"As well as being a great talent, he was a great human". Asked directly by DeGeneres if she was happy with Miller, she said, "Yes".
Asked if he knew about the engagement, he said, "I kind of knew, but not really".
The Rockstar musician, who was spotted for the first time since writing off his $323k Rolls Royce in a vehicle crash, joined an array of A-list stars in sharing their condolences on Twitter, as artists Chance the Rapper, Kehlani and J Cole also posted touching messages on Mac's passing.
Less than 24 hours before his death Miller had spoken of his eagerness to go on tour an play his new material for fans. I wish it started tomorrow. He left a short time later.
Miller was born to a Christian father and Jewish mother in Pittsburgh. "And I don't want just sadness either". A lot of people are hurting.
Fellow hip hop stars Chance The Rapper, J Cole and Snoop Dogg paid tribute to Miller on Twitter. Some of those included "You lowkey evil", "THIS IS YOUR FAULT", "It's insane because you really did kill him", "I HOPE YOURE HAPPY WITH PETE", and "You did this to him, smh".
An investigation into Mac's death is underway, authorities have said. Neither did the Los Angeles County Medical Examiner-Coroner's office.
Police were reportedly alerted to Miller's alleged overdose when a male friend called 911 from the rapper's home.
He was found unresponsive at his home in the Studio City neighborhood and pronounced dead.
Miller's death comes several months after he ended a high-profile, two-year relationship with pop superstar Grande, who was often seen as the inspiration for his songs.
Grande gave a lengthy response, calling her relationship with the rapper, and his sobriety, "toxic".