The 26-year-old was presented on Friday.
"It feels really good. It's fantastic that everything is in place now. I've got a very good impression of the club. Then I got a presentation of how the team plays and the project that's going on from the coaching team, and it was very appealing," says Dahlberg.
Lillestrøm took the step up to the top league Eliteserien after winning the Norwegian second division last season.
Dahlberg broke through at IFK Göteborg in 2017 and was signed by Watford the following year. After several seasons abroad, he returned to Blåvitt in 2022. During his final time at the club, he was primarily the second goalkeeper behind Elis Bishesari.
