Valiante began racing in karting where his success earned him a full-season scholarship in the Skip Barber 2.0 Series. In his first season, Valiante was both series champion and rookie of the year. Following this success he moved on the Barber Dodge Pro Series and then to the Toyota Atlantic Championship.
Driving for the Lynx Racing team in 2001, Valiante was able to finish eighth in the series championship despite competing in only five events. His performance impressed Lynx enough to sign him for two more seasons. 2002 was Valiante's best year in the series. He won three races and led the points going into the final round in Denver, only to struggle in the race and lose the championship to Jon Fogarty. Valiante led the series early in 2003. However, his championship hopes were dashed when he missed the fourth round at Mazda Raceway Laguna Seca due to an illness. He went on to finish third in the championship and again scored three victories.
Valiante was set to make his debut in Champ Car at California Speedway in 2003, but the race was cancelled due to wildfires in the area. It was not until a year later that he made his first Champ Car start in Mexico City. His second start came at Portland in 2005 as a one-off drive for Dale Coyne Racing. He was not able to secure a full-time ride in the series due to his lack of financial backing.
In 2006, Valiante competed full-time with Finlay motorsports in the Grand-Am Rolex Sports Car Series, where he and co-driver Rob Finlay finished ninth in the final standings. In 2008 he switched to SunTrust Racing to partner Max Angelelli in a DP class Dallara Pontiac, winning at Sonoma.
The Canadian joined Michael Shank Racing for the 2009 Rolex Sports Car Series. Driving a Riley Ford with John Pew as co-driver, he collected two podiums and resulted seventh in the DP drivers standings. In 2010 he partnered Brian Frisselle at the Shank team. With a best result of third, he finished ninth in the standings.
In 2012 he alternated between the Rolex Sports Car Series and American Le Mans Series. He started five Rolex races, winning at Mid-Ohio with teammate Richard Westbrook. In ALMS he competed in five rounds with JDX Racing in the GTC class, collecting three third-place finishes.
The driver returned to Michael Shank Racing for the 2013 Rolex Sports Car Series, having John Pew has teammate during most races. He collected two second-place finishes and resulted 15th in the DP standings.
In 2014, Valiante moved to Spirit of Daytona to race at the merged United SportsCar Championship. in the Spirit of Daytona Corvette Daytona Prototype with Richard Westbrook and Mike Rockenfeller.
(key) (Races in bold indicate pole position) (Races in italics indicate fastest lap)