[1] Trained in the youth ranks of Hammarby IF, Werner made his debut in Allsvenskan, the domestic top tier, for the club in 1971, at age 17.
[1] Between 1971 and 1976, Hammarby consistently finished mid-table, being unable to produce any sort of challenge for the Swedish champion title.
During this period, Werner became one of Hammarby's most important players, together with experienced Tom Turesson and other younger talents like Jan Sjöström, Kenneth Ohlsson and Ronnie Hellström.
In the finals against IFK Göteborg, Hammarby won 2–1 in the first leg away, but lost 1–3 in the home game at Söderstadion to a record crowd, missing out on the gold medal.
[5][6][7] Throughout his time at Hammarby, Werner went on trial with German giants Bayern Munich and reportedly attracted interest from Standard Liège, Kaiserslautern and Toronto Blizzard.