He could have made a career in the sport, however his elder brother Erik was having success as a pro cyclist and this persuaded Roger to try cycling.

[5] De Vlaeminck turned professional at the start of the 1969 season with Flandria-Declerck and won the Omloop "Het Volk" in his first race.

His skills as a cyclo-cross rider made him an expert on the cobbles of northern France which the race crosses.

De Vlaeminck used the early season Italian stage race Tirreno–Adriatico as training for the spring classics.

[6] De Vlaeminck is one of only three riders to have won all five 'Monuments of Cycling' (i.e., Milan–San Remo, Tour of Flanders, Paris–Roubaix, Liège–Bastogne–Liège, and the Giro di Lombardia).

In total De Vlaeminck won 11 Monument races, and finished in the top ten on an additional 25 occasions.

De Vlaeminck also had a few successes on track, with several podium finishes in Six-Day races and a national Madison title in 1972 alongside Patrick Sercu.

In 1970, Rik Van Looy ended his career and many fans then focused on Roger De Vlaeminck as his successor.

In April 2004 he quit his job as coach to the John Saey-Deschacht team in Belgium to spend more time with his family, However he was tempted back to the sport in November 2004 as advisor to the Zimbabwe team as it prepared for the world championship in St. Wendel, Germany, at the end of January 2005.

[citation needed] De Vlaeminck is also known for his harsh opinion of Tom Boonen, calling him unworthy of equaling his Paris–Roubaix record of 4 wins, claiming cycling is not as hard as it used to be.