Séphériadès was born in Paris. He rowed for SN Basse Seine in the single scull and was rowing champion of France from 1942 to 1946. In the closing stages of World War II he served in the Deuxième Division Blindée commanded by General Leclerc.
In 1946 he became the first French winner of the Diamond Challenge Sculls at Henley Royal Regatta beating John B. Kelly Jr. in the final. He rowed in the single scull for France at the 1948 Summer Olympics reaching the semi-final.