The former Supreme frontwoman is the first act to be announced for the British music festival, which will celebrate its 50th anniversary next June.
Diana Ross will perform in the "Legends" slot at Glastonbury 2020, which will be held from June 24 through 28.
The Motown icon will play on the Pyramid stage on the final day of the music festival -- a slot that is usually one of the biggest attractions of the weekend.
This year, Kylie Minogue made her Glastonbury debut during the aptly-called "Legends" slot in front of 3.9 million viewers tuned in to the BBC.
As the Guardian pointed out, the Australian superstar became the most-watched Glastonbury performance ever on the British TV channel, surpassing Ed Sheeran's record of 3.1 million viewers.
Diana Ross shared the news of her participation in Glastonbury 2020 on Twitter, writing "This is a dream come true. To all the fans across the world, this is my tribute to you. I'm coming to Glastonbury, with love."
Tickets for the 50th anniversary edition of Glastonbury went on sale on October 6, selling out in 34 minutes.
A record number of fans tried to secure one of the 135,000 tickets on sale, as more than 2.4 million people had signed up for a chance to attend the music festival.
"We have now sold out. Thank you all for your incredible, continued support. Demand was higher than ever ... Bring on 2020!," Emily Eavis, who is Glastonbury's co-organizer, tweeted.
We have now sold out. Thank you all for your incredible, continued support. Demand was higher than ever, with over 2.4 million people registered. Bring on 2020! https://t.co/a31IfvB4Vk— Emily Eavis (@emilyeavis) October 6, 2019
To this date, no acts have been confirmed for Glastonbury 2020 with the exception of Ross.
Taylor Swift, Fleetwood Mac and Paul McCartney are among the bookmakers' favorites to headline the weekend of music, as they will all be touring across Europe next summer.
"I'm starting to think about whether I can or whether it would be a good thing. My kids are saying: 'Dad, we've got to talk about Glastonbury.' I think I know what they mean," McCartney recently told The Zoe Ball Breakfast Show on Radio 2.