Jan Kuczyński was born in Vilnius, which was then part of Poland. Resettling in Gdańsk after the war, he pioneered freestyle wrestling in Poland, while also competing in Greco-Roman. Nationally, he won eight Polish titles between 1954 and 1962. His best result at World Championships came when he placed 5th twice (1957, freestyle and 1958, Greco-Roman). His only Olympic appearance was brief, being eliminated after just two matches. Later on, Kuczyński became a wrestling coach, also training the national team in the early 1970s. He was also active in the board of the regional wrestling association of Gdańsk, and as a referee.