The singer is raring to join Will.i.am, Jennifer Hudson and Tom Jones on the ITV show, saying: “I'm absolutely buzzing about being a coach on The Voice UK and can't wait to sit in the big red chair alongside will, Jennifer and Tom.
"I'm excited to mentor new artists and without doubt, I'm in it to WIN!"
The announcement comes just days after The Sun exclusively revealed he would be replacing axed judge Gavin Rossdale.
Last year's finalist Jamie Miller is also joining the fold as the new backstage reporter, bringing all the behind the scenes gossip to The Voice UK’s digital platforms.
Since appearing on the show, Jamie has signed a US recording deal with Atlantic Records, home of Ray Charles, Aretha Franklin and Bruno Mars.
He said: “I'm so excited to be back, but this time on the other side watching people achieve their dreams. The Voice UK was always something so close to my heart so to return as the backstage reporter is incredible!”
Meanwhile Olly's decision to join the programme is said to have annoyed his former mentor and colleague Simon Cowell, who had considered the Essex boy a member of the “X Factor family”.
Olly was discovered on the show in 2009 and returned to co-host with Caroline Flack in 2015, taking over from Dermot O’Leary.
A TV insider said: “It’s a huge coup for The Voice to have Olly on board.
“He’s got talent show experience, comedic charm and a huge fanbase. His personality will shine through as a coach.
“It won’t be like when he presented X Factor when he had to remain impartial.”
The insider added: “Simon isn’t happy Olly’s swapped allegiances, especially as he left the X Factor to concentrate on his music.”
Earlier this year, The Sun revealed that 51-year-old Bush frontman Gavin was dropped by The Voice bosses who believed he “lacked charisma”.