Íþróttafélagið Fylkir, usually known by the simplified name of Fylkir, was first established under the name KSÁ back in May 1967. Founded in Árbær, a suburb in the city of Reykjavík, by a group of youngsters, the team are nicknamed Fylkismenn and have enjoyed occasional success in domestic competitions throughout history. Fylkir also have a feeder club lower down the Icelandic league pyramid, Elliði, who provide youth team players with opportunities to play first-team football.
Fylkir first entered into competitive play on a national level in 1972 and started out in the country's third tier. The 1977 season saw the club achieve promotion to the second tier and in the years that followed, the team bounced up and down between the divisions. Finally, in 1989, Fylki made their debut in the country's top flight. However, they have suffered relegation from the division on multiple occasions and achieved their last promotion to the Úrvalsdeild in 1999.
In the 2000 season, Fylkir came close to winning their first major honour, as they finished as league runners up. The following year, they were able to lift the Icelandic Cup, after beating KA in the final. Then, in 2002, they were able to retain the trophy, this time defeating Fram in the cup final. The 2002 season also saw Fylkir finish as league runners up once again. To date, their two 2nd-place finishes remain their best ever performances in the league.
Over the years, a number of Iceland international players have played for Fylkir, with some of the most notable examples including Ólafur Ingi Skúlason, Haukur Ingi Guðnason and Helgi Daníelsson. Skúlason and Daníelsson were both products of the Fylkir youth academy and both had multiple spells with the side.
Fylkisvöllur has hosted the club's home games since their promotion to the Úrvalsdeild in 1999. The venue has undergone a number of renovations in the years since and is currently able to hold a maximum of 5,000 spectators.