The 29-year-old Ängelholmskillen has been close to a transfer to Schalke 04, Sportbladet states.
But due to poor finances, it was instead Cologne who managed to recruit the Swedish national team striker, who sat on the bench last in Sweden's match against Portugal.
Andersson, who in the Allsvenskan represented Kalmar FF, Djurgården and IFK Norrköpng, has for three years in Germany played for Kaiserslauten where he scored 12 goals in 29 matches and Union Berlin where he scored 24 goals in 67 matches.
- New challenges are important to me.
In Berlin, I have developed game-wise and personally over the past two years.
The move to Cologne is the next step, he says to Cologne's website.
According to the German newspaper Kölner Stadt-Anzeiger, Cologne has paid around five million euros for Sebastian Andersson (just over 50 million kronor).
KLIPP: Here Sebastian Andersson scores the first goal after the restart. (31 May 2020)
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Sebastian Andersson.
Photo: Bildbyrån