Leona Lewis has joined 'The Voice'.

Leona Lewis

Leona Lewis

The former 'X Factor' winner will star on the rival singing show as a celebrity mentor on Jennifer Hudson's team to give advice to wannabes about the songs they will take to the stage to perform in the knockout round next month.

Jennifer said: "I'm so excited that Leona is joining me as a mentor on Team JHud.

"I can't wait to hear what wonderful advice she has for each act. She is incredibly talented and I really trust and respect her opinion."

Jennifer will also be reunited with last year's winner Mo Jamil, who will join Leona on her team.

She added: "I'm also happy to welcome back Mo, who knows first-hand just what it takes to win this show. I think that will be a valuable point of view for the entire team."

Leona has enjoyed working with the 36-year-old singer, who she previously worked with on song 'Love is Your Colour' for the 'Sex and the City 2' soundtrack.

She said: "It's been great meeting all the talented singers and working with Jennifer.

"It's a beautiful thing to play a part in nurturing homegrown talent, to even have a small role in their journey is something very special."

Mo added: "I'm so excited to be back with my 'Voice' family and Team JHud where it all began."

Leona, 32, shot to fame after winning the third series of 'The X Factor' in 2006 and a recording contract with Simon Cowell's label Syco Music, but she later left the label after seven years.

Simon tweeted at the time: "Congratulations Leona. We had 7 great years together and now wish you all the best for the future. You put X Factor on the map (sic)"