József Berta started playing football for the local team in Szigetvár. In 1934, due to financial difficulties, he moved to Tokod, where he worked as a carpenter at the Tokod Glass Factory and played alongside the local amateur team as a left-back. As a member of the Hungarian amateur team, he was selected for the Berlin Olympics, where he and the Hungarian team played only one game, a 3-0 defeat against Poland. In 1940, the Tokodi Üveggyár SC was promoted to the first division, where Berta was one of the team’s strengths. After a one-season appearance in the first division, he became a pro in France and later settled there.
In 1936 he ran between Tokod and Dorog as a member of the torch relay that preceded the Olympics and passed through Hungary.