Starting in 1962, drove Roger Swerts as an amateur international races. In 1964 he took part in the road race in the Olympic Games in Tokyo in part, finishing in 18th place. The following year, he stepped over to the professionals and was third in the Road World Championships in Lasarte- Oria Spanish, behind Tom Simpson and Raymond Poulidor. He was the only Limburger, who was previously on the podium at a World Cup.
Swerts 1969 won the championship of Zurich, in 1971 the National Sluitingsprijs, 1972 Gent- Wevelgem, the Grand Prix des Nations, together with Eddy Merckx and the Trofeo Baracchi. In 1974 he became Belgian champion in the road race and won at the Tour of Belgium.
In the first three years as a pro Roger Swerts drove, who was an outstanding time driver for the Mercier cycling team with Poulidor, but could not prevail as Belgians among the French. He then set off in Merckx dominated by teams and could not develop his talent, joined the team, but later returned in a team with Merckx. Seven times he participated in the Tour de France in part, his best finish was 14th place in 1972. During this tour he also won the mountains classification at the Col du Tourmalet. In the Vuelta a España, he was ninth in 1973 and 1974 tenth overall.
After the end of his active cycling career was Swerts chauffeur of a Belgian minister, then sporting director of various cycling teams.