Christiansen, a native of Ft. Francis, Ontario, further developed his hockey career when he moved across the border and began his outstanding high school career while playing for International Falls, MN in the early 1960s. During those years, he helped lead the Broncos to the 1962 Minnesota State High School Hockey Championship while being named to the All-State Team.

Moving on the Division I hockey at the University of Minnesota – Duluth, Christiansen was a key figure in helping to elevate the UMD program into national prominence. During his career, he amassed 196 points in 102 games and shared the UMD record for the most points scored in one game (6) which occurred in the inaugural game at the Duluth Arena against the Minnesota Golden Gophers. He was the first UMD Bulldog to lead the WCHA in scoring and was named the leagues' player of the year in 1966-67. Other collegiate honors include MVP as a freshman, junior, and senior, NCAA All-American and all WCHA first team in 1966-67, and UMD's Outstanding Senior Athlete Award in 1966-67 after he was team captain. In 1988, Christiansen was granted the honor of being the only UMD athlete to have his jersey (#9) retired.

In International competition, Christiansen represented the United States at the 1969, 1970, and 1971 World Tournaments. He was captain and one of the leading scorers for the 1972 silver medal winning United States Olympic Team in Sapporo, Japan.

In 1972, after the Olympic Games, Christiansen went to play major league professional hockey and was signed by the Minnesota Fighting Saints in the newly formed World Hockey Association (WHA). He retired from hockey in 1975 after helping the Fighting Saints to the playoffs in 1972-73 and 1973-74.

Christiansen became a Charter Member of the University of Minnesota-Duluth, Athletic Hall of Fame in 1991, was honored as one of the "Top 50 Players in 50 Years" of the WCHA in 2002, and was inducted into the Duluth Entertainment Convention Center Athletic Hall of Fame in 2004.