In his early career he played for IFK Visby, Visby AIK and IFK Norrköping.[1] Having been benched 5 times for Norrköping's senior team in 2009, he moved back to Gotland and FC Gute in 2010, and made his senior debut for that club in the 2011 Division 2.[2] After the season, he was given the GA Ball as the Player of the Year in Gotland.[3]
In 2012, Fagerström started playing for Nyköpings BIS.[4] After many years in Nyköping, he was signed by Örebro SK in July 2016 as a replacement for Jacob Rinne.[1] He was out of contract at Nyköping.[5]
After one year, Fagerström had still not played a league game and was doubtful regarding a renewal of his contract.[6] Fagertröm ended up not playing a single league match for Örebro. He moved to Ettan club Västerås SK in 2018, winning promotion to Superettan in his first season.[7] In 2019, interest in him was reportedly shown by Swedish teams as well as a Greek club.[8]
In the 2023 Superettan, Fagerström experienced a career highlight as he was named Goalkeeper of the Year and Västerås won promotion to the 2024 Allsvenskan.[9] He made his Allsvenskan debut on 1 April 2024 at the age of 32.[7]
Västerås suffered relegation after one season. Fagerström's contract was also about to expire,[10][11] but before 2024 was over, a one-year extension through 2025 was announced.[12]