Fabiański began his career at the Polish club, Lech Poznań, where he made his professional debut in 2004. He quickly established himself as one of the top young goalkeepers in Poland and was signed by Arsenal in 2007. Fabiański spent seven years at Arsenal, primarily serving as the backup goalkeeper to the legendary Petr Čech. Despite limited playing time, Fabiański impressed with his performances in cup competitions and was praised for his professionalism and work ethic.