Knowles was rumoured to be joining the BBC One competition, which has been mired in controversy because of complaints from former contestants.
He was revealed on the BBC’s The One Show on Monday.
Knowles, who was the 13th celebrity named, said: “I’m so, so excited to be doing Strictly this year. People may be more used to me getting stuck in on a building site or travelling the world, but dancing live on TV will be a whole new adventure.
“I’ve spent my whole life learning new skills and I’ve never been afraid of a challenge – there’s life in the old dog yet to take on one more big one – being taught how to dance! I’ll give it my everything … and try not to embarrass my kids of course.”
The 61-year-old has had a long career at the BBC and is known for long-running renovation programme DIY SOS and former gameshows Who Dares Wins, which ended in 2019, Break The Safe and 5-Star Family Reunion.