Career
In the 2005-2006 season, Berglund played for VIK Västerås in the HockeyAllsvenskan, the second highest league in Sweden. He was a top prospect in the 2006 National Hockey League Entry Draft and was drafted 25th overall by the Saint Louis Blues. He scored his first National Hockey League goal on 13 October 2008 against Vesa Toskala of the Toronto Maple Leafs.
Paired on a line (called the "Kid Lincolnshire" by Blues fans, due to the oldest player on the line being 22) with David Perron and his flatmate T. J. Oshie, Berglund became a scoring threat in Saint Louis" surprise 2008-2009 season, finishing the year with 21 goals and 26 assists for 47 points in 76 games.
During the 2012-2013 National Hockey League lockout, Berglund returned to Sweden to play for VIK Västeråson On 25 June 2013 Berglund signed a one year $3.25 million contract extension with the Blues.