His agency Lookout Management confirmed Roberts' death in a statement, but no other details were shared.
Born Elliot Rabinowitz, Roberts grew up in New York but later moved to California, where he met David Geffen and became immersed in the 1960s and '70s rock music scene.
In addition to Young and Mitchell, Roberts went on to manage artists like Crosby, Stills and Nash; the Cars; Tracy Chapman; Tom Petty and others. He managed Mitchell until 1985, and Young right up until Roberts' death.
Roberts also founded Asylum Records, which put out records by the likes of Jackson Browne, Linda Ronstadt and the Eagles.
Young posted a tribute to Roberts on his website on Saturday (June 22).
"Never one to think about himself, he put everyone else first," Young wrote. "That's what he did for me for over fifty years of friendship, love and laughter, managing my life, protecting our art in the music business. That's what he did."
Others have also shared memories of and tributes to Roberts via social media. See some of those below.
I liked Elliot Roberts a lot. He was a kind, thoughtful, and helpful man. So sad to hear of his passing. Love always.— Flea (@flea333) June 22, 2019
Met this guy on the road and he was one of the good ones - a classy, lovely guy . Sleep with angels ❤️ Neil Young Pens Tribute to Late Manager Elliot Roberts | Pitchfork https://t.co/T5xcLldhDm— Courtney Love Cobain (@Courtney) June 23, 2019
Saddened by the passing of Elliot Roberts. He laid the blueprint for how to manage us crazy artists and our bizarre, longshot careers. Grateful to those who make it possible for us to work and be happy.— Jason Isbell (@JasonIsbell) June 22, 2019
I loved Elliot Roberts. He made me feel like I was good at music, gave me advice that changed my life, and took care of me when I was in trouble. He was also the funniest person I've ever met. I can't believe I'm not gonna hang with him again. https://t.co/M4hJNkG07C— matt sweeney (@theheavyjamz) June 22, 2019
RIP Elliot Roberts. Elliot was Tom Petty and the Heartbreakers Co-manager together with Tony Dimitriades 1978-1988. He was a dear friend of the Heartbreakers family and will be deeply missed by all. (📷: @LinerNoteJunkie ) pic.twitter.com/MyrpNZQpsE— Tom Petty (@tompetty) June 23, 2019
After scouring the internet for the perfect photo of Elliot Roberts, I finally came across this image that captures his two finest qualities, love and humor. Sending strength and love to his friends and family. Rest In Peace Elliot, see you on the next level 📸: far out magazine pic.twitter.com/zB9ubVFpTz— Lukas Autry Nelson (@lukasnelson) June 23, 2019
We lost a friend today, someone who truly believed in our band, made our wildest dreams come true and was always there to show support even from far away. RIP Elliot, thank you for everything. Keep on rocking! ♥️#elliotroberts love this pic of him & Neil 😢 pic.twitter.com/scAblx3R1X— The Magic Numbers (@themagicnumbers) June 22, 2019
So sad to hear of the great Elliot Roberts passing on. He was a giant among artist managers and was always a friend to my manager, Scooter Weintraub, and me. https://t.co/TObB1oZZV8— Sheryl Crow (@SherylCrow) June 22, 2019