Stevie Wonder will get a kidney transplant later this year, he told a festival crowd Saturday night in London. A donor has been lined up, he said.

"I'm going to have surgery," he said. "I'm going to have a kidney transplant in September of this year. It's all good. ... I have a donor."

Wonder's announcement follows a week of speculation about his health. The Detroit Free Press reported Wednesday that the Motown star was battling a serious medical condition.

More:Stevie Wonder has ongoing medical issue but remains in 'great spirits,' friends say

"I want you to know, I came here to give you my love, and to thank you for your love," the 69-year-old Wonder told the audience at the Barclaycard British Summer Time festival in London's Hyde Park. His announcement spurred a roaring round of applause from the concert crowd.

"So you ain't got to hear no rumors about nothing," said Wonder, sounding upbeat. "I told you what's up: I'm good."

Wonder was hospitalized this spring and has been traveling with a medical team as he continues to perform, the Free Press reported. Friends of the iconic singer said he has remained in good spirits amid the health issues.

He had also hoped the situation would remain private, they said, but speculation about his health began popping up online last weekend.

One friend said the public chatter was “turning into exactly what he didn’t want. He’s not too thrilled about it.”

The Saginaw-born, Detroit-raised Wonder is among the most elite and musically prolific acts to rise out of Motown Records in the '60s. He has remained one of Detroit's most beloved and decorated artists in the decades since, piling up 25 Grammy Awards and continuing to play regularly at sold-out venues around the world.

Saturday's news prompted an outpouring of support from fans, friends and members of the Motown family.

"Stevie Wonder is a treasure and force in our culture. He is a master of music and humanity," Motown Museum CEO Robin Terry said in a statement late Saturday. "His Motown Museum family is in touch with him and we are praying for his full recovery and return to the stage where he will continue to be an inspiration for us all."

Wonder's most recent hometown concerts were in 2014 and 2015, when he played the Palace of Auburn Hills and Joe Louis Arena as part of a tour celebrating his classic album "Songs in the Key of Life." Wonder also closed Aretha Franklin's nine-hour funeral in Detroit last August.

The Free Press has reached out to Wonder's team for more information about his Saturday announcement.

Contact Detroit Free Press music writer Brian McCollum: 313-223-4450 or bmccollum@freepress.com.