Sixten Vilhelm Paul Ammerfelt was born on November 21, 1911 in Göteborg and made his IFK Göteborg debut in the 1933/34 season, which was also the debut season of team mate Olof Hultfeldt. Ammerfelt (Andersson) was part of IFK Göteborg's youth program before making his debute with the first team, and is as a result of that regarded by the club as a home-grown player. At 22 years, 5 months and 7 days, on April 29, 1934, he took part his first competetive game against IS Halmia in an Allsvenskan game that ended 3–1. He spent two seasons with the IFK Göteborgs first team, and during his career he played in 5 first team games and scored 3 goals. Out of these 5 first team games, 2 were Allsvenskan games.
Sixten Ammerfelt (Andersson) is with his 2 Allsvenskan games number
456 on the list of those who have competed in most Allsvenskan games for IFK Göteborg. Ammerfelt (Andersson) passed away in 1998, 86 years old.