The drummer revealed that he was a fan of the X Factor star and described her interpretation of Snow Patrol's 'Run' as "wonderful".
Speaking to CFM Radio, Champion said: "[Leona Lewis] is brilliant, I think. Amazing voice. She did a fantastic cover of the Snow Patrol song ['Run'], it was wonderful."
Coldplay recently admitted that they have no plans to collaborate with other artists in the future, following their Rihanna hook-up 'Princess Of China'.
Previously talking about their decision to collaborate with another artist, Champion explained: "We questioned whether we should have anyone sing on our album because we hadn't done it before, is it cool to do that?
"Or is it cool to get somebody who's got such a huge profile to be the other half of the duet? Or should we get somebody that has a great voice that is completely unknown?"
He added: "We all love Rihanna and we came to the decision that if we are going to get someone to come and sing on it, it should be the best person and she's obviously an incredible artist.
"She was the original intention for the female part, so it just had to be her really!"
Coldplay and Rihanna's new single 'Princess Of China' is out now.
Watch the music video for Leona Lewis's 'Run' below: