Ulf Dahlen was selected seventh overall in the 1985 NHL Entry Draft by the New York Rangers. At the time, Dahlen was the second-highest drafted Swedish player ever taken in the history of the draft. NHL scouts noticed Dahlen after he captained Sweden's under-18 junior team at the 1985 European Junior Championships and was named the tournament's Best Forward after scoring eleven points in five games.
Dahlen made his NHL debut in 1987 and had a solid rookie year, collecting 29 goals and 23 assists for 52 points. The following year Dahlen was mildly hit by the sophomore jinx, being limited to only 56 games due to a shoulder injury.
In 1989-90, Dahlen was traded to the Minnesota North Stars and in just over three years with the North Stars, Dahlen scored 94 goals and was a driving force in helping the club advance to the Stanley Cup finals in 1991, where the Stars eventually lost to the high-powered Pittsburgh Penguins.
Dahlen's most productive season came in 1992-93 when he had 35 goals and 39 assists for 74 points. Voted co-most popular player with Mike Modano amongst his Minnesota teammates Dahlen and the North Stars moved to Dallas in 1993-94.
On March 19, 1994, Dahlen was traded to the San Jose Sharkds and in 78 games between the two teams, registered 25 goals and 69 points. During the 1996-97 season, Dahlen was traded to the Chicago Blackhawks and in 1998, represented his homeland at both the Winter Olympics and the World Championships, where he helped Sweden capture the gold medal.
Dahlen signed as a free agent with the Washington Capitals in 1999 after spending the previous two years in his homeland and went on to play two more seasons with the club before re-joining the Dallas Stars in 2002-03. After only one season in Dallas, Dahlen decided on calling it a career.