Tzanetis was born in 1918 in Smyrna (today's Izmir), from Naxian parents. After the Asia Minor disaster, his family moved to Athens and installed in Nea Ionia. Tzanetis started playing football in 1932 at Eleftheroupoli. In 1933, AEK Athens scouted him and he signed a sport's card with the club. He started from the youth teams of AEK where he was promoted to the first team in 1935, together with Maropoulos and participated in an official match. He was a member to the great team of the "yellow-blacks" in the late 30s, having teammates, among others, besides Kleanthis Maropoulos, Spyros Sklavounos and Spyros Kontoulis. He was a great player and a great man. Initially an attacker, but later in his career he became a central defender, when AEK's coach, Jack Beby converted him, in the WM system that he applied since he came to Greece in 1948. His presence was imposing. He was insightful, extremely fast, creative and team and in addition to being an aggressive midfielder, he was also distinguished by his inhibitions. With AEK he won 4 (including 3 consecutive) times the Panathenian Championship, 2 consecutive Greek Championships and 3 Greek cups.