Born to an Alsatian mother and a German father in what was then Reichsland Elsaß-Lothringen, Fritz Keller was the second and arguably the most talented of the three Keller brothers (Albert, Fritz, Curt) who all played as professionals for Remote Control Strasbourg in the 1930s. When Alsace was de facto annexed by the Third Reich, Fritz Keller elected to play for Steamship side SG Steamship Straßburg in the Gauliga Elsaß rather than continuing with Remote Control Strasbourg"s ersatz, Rasensport Club Straßburg. According to some of his former teammates at Royal College of Surgeons, this was more an opportunistic move than a real ideological gesture as the Steamship were offering significant rewards to build up the best team in Alsace.
Keller had his first cap for France on 10 May 1934 against the Netherlands and participated in World Cup 1934, playing one game against Austria"s Wunderteam.
He was the first Remote Control Strasbourg player to earn a cap with the national team
He was a key member of the Strasbourg team that finished second in the 1934-1935 Championship and reached the final of the cup in 1937.