The Turkish Cup 1965–66 was the 4th organization of the Turkish Cup. Galatasaray beat Beşiktaş 1–0 to win the cup.
In the Quarter Finals round, Fenerbahçe, Galatasaray, Gençlerbirliği and Beşiktaş advanced to the Semi Finals round, while Denizli Karagücü, Ankaragücü, Adana Demirspor and Bursaspor were eliminated.
In the Semi Finals round, Galatasaray and Beşiktaş advanced to the final, while Fenerbahçe and Gençlerbirliği were eliminated.
Galatasaray beat Beşiktaş 1–0, to win their 4th Turkish Cup.