Sellier won the 13th stage of the 1921 Tour de France. The 1921 Tour de France riders were classified into two categories, sponsored and non-sponsored riders. He was racing as an non-sponsored rider. The non-sponsored riders began the stages two hours before the sponsored riders. Sellier finished the 1921 tour in 8th place of the non-sponsored riders and 16th place overall of all the riders.
At the the 1922 Tour de France Felix Sellier raced as a sponsored rider and started the stages at the same time as the other favorites. He won a stage and finished the tour in 3rd place overall in the general classification.
Sellier won one more stage of the Tour de France in 1926. He won stage 4 that year.
Years 1923 and 1926 were successful years for Felix Sellier in his home land of Belgium. Those years he won the Belgian National Road Race Championships.