He started his career at local amateur club Damlacık in 1952 and moved to another amateur side Yün Mensucat the following season during which he was able to make his debut for the junior national team in 1954. He was quickly transferred to İzmirspor at the end of the season and became top-scorer with 17 goals in the İzmir League next season, the first of many times that he would lead the top scorers in the league. In 1955, Gündüz Kılıç, trainer and former footballer of Galatasaray SK transferred him. Oktay, then only 19 years old, signed a five-year contract with Galatasaray in exchange for a Chevrolet car. Despite his young age, he was top-scorer in his first season in the Istanbul League, with 19 goals, and his team Galatasaray won the championship. Metin Oktay was top scorer for 4 seasons in the İstanbul League and then 3 more in Turkish League thus making it 7 consecutive years in the competitions he played in.
Oktay made a record-breaking contract with Galatasaray in 1960 and because of this deal he had to divorce from his wife Oya Sarı who wanted him to play for his old club İzmirspor. In December that year he scored four goals (1', 9', 61' and 71' min) in a 5-0 victory against arch rivals Fenerbahçe which fixed his hero status among Galatasaray supporters. The songs were made for him and he became the first-ever Turkish footballer who played himself in a movie based on his life while actively pursuing his career.
Metin Oktay kept wearing Galatasaray shirt until 1969, with the exception of a short period in 1961-1962, when he played for Palermo, Italy. He was the most crowned (six times) top goalscorer in Turkish League and set a record with 217 goals in total. Tanju Çolak broke his record of most goals in a season in 1988 by a margin of one goal. Nicknamed the Taçsız Kral or "King without a crown", he was a particularly strong goal scorer in derby matches. During a derby match against Galatasaray's archrivals Fenerbahçe in 1959, he hit the ball hard enough to open up a hole in the opponents' net. This unforgettable shot was one of the 18 goals Oktay scored against Fenerbahçe in his career. The other major Istanbul rivals, Beşiktaş let in 13 of his goals. Metin Oktay also served as assistant coach & head coach of Galatasaray football team in the season 1969-70¹ and he later coached Bursaspor for a couple of years. Metin Oktay was a board member of the club in 1984 for two years.2
He played 36 times for the Turkish national team and scored 19 goals. Breaking almost every record in the history of Turkish football that stood at the time, the "King" retired in 1969. Metin Oktay died on September 13, 1991 in Istanbul following a tragic car accident.
Every year on September the 13th, Galatasaray players and supporters pay homage to the "Uncrowned King" alongside his grave at Kozlu cemetery near Topkapı in Istanbul.
Galatasaray's sports complex and training facility, the Metin Oktay Sports Complex and Training Center, located in Florya, Istanbul, is named after him.