The Back To The Beginning show on July 5 will include the 76-year-old singer deliver his own short set before he joins bandmates Tony Iommi, Geezer Butler and Bill Ward - who will play together as a group for the first time in 20 years.
"I'll be there, and I'll do the best I can. So all I can do is turn up," he told the Guardian.
In 2020, Osbourne revealed he had been diagnosed with Parkinson's disease and he paused touring in 2023 after extensive spinal surgery.
"You wake up the next morning and find that something else has gone wrong. You begin to think this is never going to end," he told the paper.
He said the reunion concert was conceived by his wife, Sharon, as "something to give me a reason to get up in the morning".
"I don't think I'll be doing much jumping or running around this time. I may be sitting down," he added.
Former Van Halen frontman Sammy Hagar told rock radio show Loudwire Nights that he was informed Osbourne is "going to try and sing five songs", including No More Tears.
Osbourne had a fall at home in 2019 which aggravated injuries from a near-fatal quad bike crash in 2003.
The all-day event at Villa Park in Birmingham, the city where the heavy rock pioneers formed in 1968, will also feature sets by a host of major metal bands including Metallica, Slayer and Alice In Chains.
In 2017 the band played what was billed to be their "last" gig with Osbourne, guitarist Iommi and bassist Butler - but without Ward on drums.
Black Sabbath's story began when Osbourne, Iommi, Butler and Ward were looking to escape a life of factory work.
Their eponymous debut album in 1970 made the UK top 10 and paved the way for a string of hit records.
They went on to become one of the most influential and successful metal bands of all time, selling more than 75 million albums worldwide.
The group were inducted into the Rock And Roll Hall of Fame in 2006, and Osbourne was added for a second time in 2024.
He previously celebrated his home city in 2022 when he helped close the Commonwealth Games.
He rose to further fame alongside his wife Sharon - who he married in 1982 and with whom he has three children, Aimee, Jack and Kelly - through their reality TV series The Osbournes.
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