Hammarby replaces fleeing Dennis Gül with a Danish striker.
Sebastian Clemmensen, 20 years old, has written a contract that extends over 4.5 years.
Clemmensen comes most recently from the Copenhagen club B93 in the Danish second division.
Hammarby's sports manager Mikael Hjelmberg says in a press release:
"He fits perfectly into the profile we've been looking for based on properties, age, and ambition. He's a fast, intense, and technically skilled offensive player with a fine left foot who can play both on the wing and centrally."
In total, Clemmensen has scored 16 goals in 37 league and cup matches for B93 since last season.
Hammarby sold striker Dennis Gül to Porto on Saturday, according to Portuguese reports, in a deal that gives Hammarby approximately 50 million kronor in the first stage.
