Signing as a free agent with the expansion Minnesota North Stars, Nanne started his National Hockey League career in 1968 following the Olympics. He would spend his entire career in Minnesota, playing 635 NHL regular season games for the North Stars through the 1977–78 season. A steady defenseman and sometime forward, he scored 21 goals in 1971–72, but was mostly known for his defensive, penalty killing abilities. Nanne played for U.S. national team in 1976 and 1977, participating in the 1976 and 1977 Ice Hockey World Championships and competing in the inaugural Canada Cup in 1976. Nanne also served as national team captain or alternate in both years.