Corinne Bailey Rae, Melissa Etheridge and Diane Birch honoured Stevie Wonder before his headlining act at Hard Rock Calling.
Corinne, who also supported the 22-time Grammy award winner at Glastonbury, revealed she was asked to sing Like A Star to him over the phone.
"I get asked often to sing down the phone, but the only person I've done it for is Stevie - because it's Stevie Wonder. He has influenced me so much and is such an icon," she told the crowd in London.
Two-time Grammy award winner Melissa Etheridge - who headlined the Pepsi Max stage - praised the Superstition star, who turned 60 last month.
"He is a genius," she said backstage.
"He's made music that is beautiful R 'n' B with a rock and roll twist. He would infuse so many different types of music into his soul, and create music you just want to move to. He's just one of the best."
US songstress Diane, who will be supporting Stevie in a gig in Nimes, France, added: "He's one of those incredibly magical musicians. He's got everything and his soul and just the kind of scope of his musicianship is just amazing."
She went on: "It's always been very inspiring to me, his ability to write an amazing song and sing it with such precision and play with such funk and soul."