[3]: 159 Champion raced behind motor-powered tandems during the 1900 season on outdoor board velodromes in cities from Boston to New York and down the east coast to Atlanta.

He competed against riders such as Jimmy Michael and Bobby Walthour Sr. Three years later, he had won 100 races in America and imported a four-cylinder motorcycle from Paris.

On 12 July 1903, Champion piloted his 350-pound French motorcycle around an outdoor board track in Cambridge Massachusetts, on what is now the MIT Campus.

By June 1904, he returned to his native Paris to raise money and found a company in Boston importing French electrical parts.

Coping with his shortened leg by using cranks of different lengths, he won the Grand Prix of Paris 50 km motorpace race on the Buffalo Velodrome and then the 100-kilometer motorpace championship on the Parc des Princes track by beating specialists such as defending national champion Henri Contenet and the "blond Adonis",[3]: 160  Émile Bouhours.

They included the prominent road riders who had won earlier editions, Maurice Garin and Josef Fischer and track specialists such as Champion, Émile Bohours and Paul Bor.

What the track riders had gained through experience in paced riding, they lost in inexperience of the cobbles and other bad road surfaces that constituted Paris–Roubaix.

In the summer of 1904 he moved back to France and won the national 100-kilometer motor-pace race on the Parc des Princes outdoor cement track.

Five months later, on 26 October 1927, Champion collapsed and died suddenly at age 49 in his suite in the Hotel Meurice after being punched by his wife's married lover in the Hôtel de Crillon.

Alfred P. Sloan, president of General Motors, said: "The keynote of Champion's success was, that he was never satisfied [...] his mind was open to the necessity for constant improvement".

In August 2015, Champion was enshrined as a life-size bronze statue in downtown Flint, part of the city's Back to the Bricks Automotive Pioneers Statute Project.