In 1961, Geesink was the first non-Japanese to become world champion judo in all categories. Anton Geesink won the gold medal judo in all categories in the Olympic games of 1964, held in Tokyo. In that year judo was for the first time on the Olympic program, as a demonstration sport. In the finals Geesink beat the Japanese judoka Akio Kaminaga.
In 1965 in Rio de Janeiro, Geesink became again world champion - as a heavyweight. In 1997, Geesink obtained the tenth dan, the highest degree in judo.