The 2008–09 Swiss Super League was the 112th season of top-tier football in Switzerland.
The competition was officially named AXPO Super League due to sponsoring purposes.
It began on 18 July 2008 with a match between Young Boys Bern and reigning champions FC Basel, which the latter won by 2–1.
FC Thun were relegated after finishing in 10th and last place in 2007–08 Swiss Super League.
9th placed FC St. Gallen and Challenge League runners-up AC Bellinzona competed in a two-legged relegation play-off after the end of last season.