Having grown up in Nea Smyrni, Mavros joined Panionios' youth ranks and soon made his way to the first team. He soon managed to become the youngest player ever to score in the Greek Super League. He was also capped by the Greek national football team at a very young age whilst playing for one of the less glamorous Greek clubs. On 16 September 1971, he made his debut in continental competitions against Atlético Madrid. His appearance made him the then youngest player of a Greek football club to have ever played in a European competition.
In 1975, AEK Athens' president Loukas Barlos wanted to sign the young striker but Panionios board refused to trade his team's best player. It was then revealed that when Mavros signed his contract with Panionios he was still underage, thus making the contract invalid. Panionios still blocked the transfer leading to a litigation between the two sides which lasted for the entire 1975–76 season. During this time, Mavros was unable to play for either side. After the dispute was resolved Mavros was finally transferred to AEK Athens in 1976. He immediately became an integral part of the team helping them reach the 1976–77 UEFA Cup semi-finals, winning two championships: and two cups. He also managed to become Greek Superleague's Top Goalscorer three times. In 1979, he was also second goalscorer in Europe, three goals behind AZ's Kees Kist. He, as a striker, and Bajević, as a creator were the club's best scoring couple and one of the best in Europe. The AEK Athens fans loved him because he was one of the few players who stayed with the club after Barlos left and because of his tendency to score against rivals Olympiacos. They called him by the nickname "The God" and whenever he scored the whole stadium chanted "Who, who, who? Mavros the God". On 22 June 1984, Mavros had the honour to be called to join World's XI alongside his countryman Vasilis Hatzipanagis and other legends like Franz Beckenbauer, Ruud Krol, Johan Neeskens, Peter Shilton, Kevin Keegan, Mario Kempes, Hugo Sánchez and Felix Magath. 20,000 Greek fans were in the Giants Stadium to watch World's XI playing against New York Cosmos in a 3–1 win. In fact, according to his statement, in the game, Beckenbauer told him "At last, you came.", meaning the constant interest of his team, New York Cosmos for Mavros.
Return to Panionios
In 1987, AEK Athens' manager Nikos Alefantos asked the club's president Andreas Zafiropoulos not to renew Mavros' contract as he thought the player was too old to play for a team of that level. Zafiropoulos agreed and Mavros was released from the club and returned to his former club, Panionios. With Panionios he finished top scorer in Greek Superleague once and, until his retirement in 1991, scored a total of 51 goals in 89 matches surpassing his former teammate at AEK Athens Mimis Papaioannou as the Greek Super League's all-time top goalscorer. A notable moment was when during a match against AEK Athens in Nikos Goumas Stadium on 28 October 1989 he scored against them but the AEK Athens fans chanted his name as if he had just scored for AEK Athens showing how much they loved and respected him.
International career
Mavros had a total of 36 appearances with Greece scoring 11 goals in the period of 1972–1984. His most notable moment was his appearance in UEFA Euro 1980.
Records
Mavros is the Greek Super League's all-time top goalscorer having scored 260 goals in 501 matches.
Mavros is the youngest player to have scored in the Greek Super League. He scored the winning goal in Panionios' 1–0 win against Pierikos on 17 February 1971 when he was just 16 years, 8 months, and 17 days old.
Mavros is one of the few players who has scored five goals in a single Greek Super League game. He did so in AEK Athens' 5–2 win against Egaleo during the 1984–85 season.
