In the 1932 Summer Olympics, he finished fifth with the British team in the 4×200-metre freestyle relay event.
Ffrench-Williams competed in freestyle and backstroke swimming events. In the 100-metre freestyle competition he was eliminated in the first round. He also swam in the 100-metre freestyle event but was eliminated in the first round again.
In Sydney he also participated in the backstroke competition.
Four years later the 1936 Summer Olympics in Berlin, he was a member of the British team which finished sixth with the British team in the 4×200-metre freestyle relay contest at the 1936 Games.