He was a member of the House of Commons of Canada from 2004 to 2008, representing the riding of Kenora for the Liberal Party.
He also served as a city councillor and mayor of Dryden, and was the president of the local provincial Liberal Party riding association for almost ten years.
The seat was left open after former Liberal cabinet minister Robert Nault announced his retirement from politics.
Valley initially won the Liberal nomination in a close contest against Charles Fox, a local aboriginal leader.
Unlike the situation in some other Ontario ridings, the nomination battle did not result in lingering divisions for the local party organization; Fox endorsed Valley during the general election.