Born on April 4, 1937 in Hungary, Portisch started his chess career at the age of 16 in his native city, Zalaegerszeg, and in 1955 he became Hungarian champion. He was recognized as an International Grandmaster in 1961, having previously been awarded the titles of International Master in 1958 and International Grandmaster in 1961.
During his career, he represented Hungary in 21 Chess Olympiads winning multiple medals and leading the Hungarian team to a first place in the 1978 Olympiad. Notably, his individual record in Olympiads is the best overall performance in the history of the event with a total of 176.5 points scored in 263 games.
Portisch was part of the top ten players in the world from the 1960s to the late '80s, and for a short time, he was in the world's top three. He has won international tournaments such as the Dutch Open Championship and the Mar del Plata Tournament. His most successful year was 1965 when he won five of eight tournaments he entered.
Known for his methodical and systematic style of play, Portisch was an expert in the handling of Rook endings. His style is often compared to that of the former world champion, Tigran Petrosian. Due to his solid and deep understanding of the game, he was often referred to as the "Hungarian Botvinnik".