Johann Weidel was one of the top amateur boxers in Switzerland in the 1920s, winning national titles in 1922, 1923, 1924. He began his career in Neuchâtel, but spent most of it based out of Genève where he trained under François Sauthier at the Salle Sauthier club alongside many other top boxers of the era. Selected to represent his country at the 1924 Paris Olympics, he competed in the bantamweight division but was unable to advance past his first match, losing to Antonio Sánchez of Spain by decision. Following the Olympics, Weidel added two additional national titles to his repertoire in 1925 and 1926, but retired shortly after.