Champion was the last of the four band members to join the ensemble on 31 July 1997. He took up the position as drummer with no prior experience, but quickly adjusted to fill the role.[1] In 1999, lead singer Chris Martin sacked Champion, but the band asked him to return soon after.[2]

In Coldplay, he is often regarded as the rationality of the group. They say of him: "Will does have a very sensible head on his shoulders and when it comes to making band decisions he's really good at putting valid points across and keeping everyone focused. He frequently has the casting vote and his decision can sometimes override the consensus!"[3] As Chris Martin has said in multiple interviews, "We [Coldplay] are all just working for Will Champion."

During the Viva la Vida Tour, Champion sang and performed an acoustic version of the song "Death Will Never Conquer". A version of the song was included on Coldplay's live album LeftRightLeftRightLeft. He has also performed lead vocals on a live version of "Til Kingdom Come" and the Life in Technicolor II b-side "The Goldrush".