Florian Kainz took his first footballing steps with FC Stattegg before joining Sturm Graz just before his seventh birthday. With Sturm, he made his Bundesliga debut at the age of 17. In the 2014-15 campaign, Kainzi joined Rapid Wien. He made his debut for Austria while with Rapid and has been part of the ÖFB setup since 2015.
In 2017, Kainz made the move to Germany and Werder Bremen, before signing for 1. FC Köln in January 2019. At FC, Kainz immediately became a key figure in the side and, despite a serious knee injury, has over 100 competitive appearances for the club. Since the 2023-24 season, Kainz is FC captain.
