Berglund started his professional career with IF Elfsborg and was a key player together with Anders Svensson and Tobias Linderoth, the three of them were nicknamed "The Headband Gang".

[1] In the 2000 season he was top goalscorer of the Allsvenskan and he attracted interest from foreign based clubs and eventually signed for Dutch side Roda JC in a €750.000 deal.

[1] In the spring of 2004 Berglund moved to Danish Superliga side Esbjerg fB who paid a record transfer fee of €150,000 for him.

[1] On 26 November 2006, he beat Erik Bo Andersen's record of quickest person to score 50 goals in the Danish Superliga.

[8] On 31 March, ten minutes before midnight and the end of the Norwegian transfer window, 2008 champions Stabæk announced that they had signed Fredrik on a season-long loan deal.

After being sidelined a long time with constant injuries, Berglund felt he no longer had the motivation to continue playing.