Defenseman Stoltz played the best years of his hockey career alongside Lars Bjorn, and this famous defense duo was regarded as one of the best in the history of Swedish and European hockey. He began his hockey career playing for the Atlas Diesel IF team while working as a mechanic for Atlas Kopco, a well-known mining machinery manufacturer in Sweden. After the Atlas team fell apart, Stoltz joined the Stockholm Djurgarden team in 1955, but only because another Stockholm hockey club, Hammarby, rejected him as a defenseman, thinking he was too slow. Stoltz began playing Swedish hockey during his formative years and he matured as he gained experience on the ice. Stoltz made an impressive debut in the Tre Kronor lineup on November 13, 1955, in a game against Norway's national team in Oslo. The game ended 7-1 in favor of the Swedes, with one of those goals scored by the rookie Stoltz, who still hadn't learned how to lift the puck.
There are probably not many who know that Lars Bjorn and Roland Stoltz feel indebted to this day to Canadian coach Ed Reigle, who worked in Swedish hockey at the end of the 1950s. It was Reigle who showed them how to bodycheck; it was Reigle who taught them the art of wrist shots and slapshots. As a former defenseman who had gone through the tough NHL school, Reigle was able to teach them a great deal about the tactics and techniques of playing hockey.
With Stoltz on the team, Djurgarden won the Swedish national championship title six times in a row. In the lineup for the Swedish national squad, Stoltz played in 199 official games without interruption from the fall of 1956 until the 1968 Olympic hockey tournament in Grenoble. In Colorado Springs in 1962, he scored the winning goal against the U.S. nationals in a crucial game for Tre Kronor on the road to the gold medal.
Stoltz twice became world champion in 1957 and again in 1962, but the highlight of his career was the 1963 World Championship in Stockholm, when he was voted best defenseman. He once admitted that his toughest opponent was Soviet forward Veniamin Alexandrov. Most memorable for Stoltz were the games against the USSR nationals in Moscow in 1957 and the Canadian team in Colorado Springs in 1962 and the Olympic hockey tournament at Innsbruck in 1964.
Adjusting to wearing a helmet during play was difficult for Stoltz, and even after they became obligatory, he refused to wear one.
He is recognized as a staunch and selfless player, qualities that epitomize the Swedish style of hockey playing. He was inducted into the International Ice Hockey Federation's Hall of Fame in 1999.