Thanasis Antetokounmpo began playing youth club basketball with the junior teams of Filathlitikos, in 2008.

He then played with the senior men's team of Filathlitikos, in the semi-professional level of the Greek fourth division (2010–11 season).

During the 2012–13 Greek 2nd Division season with Filathlitikos, he averaged 12.2 points, 4.9 rebounds, 1.0 assists, 1.1 steals, and 1.0 blocks per game.

[6] On November 1, 2013, Antetokounmpo was selected by the Delaware 87ers with the ninth overall pick in the 2013 NBA Development League Draft.

[7] On November 23, 2013, in his D-League debut, Antetokounmpo recorded 14 points, 2 rebounds, and 2 assists, in a 117–106 loss to the Canton Charge.

During the 2013–14 NBA Development League season, he averaged 12.0 points, 4.3 rebounds, 2.1 assists, 1.2 steals and 1.3 blocks in 50 games.

[9] In July 2015, Antetokounmpo re-joined the New York Knicks for the 2015 NBA Summer League where he averaged 6.4 points, 1.8 rebounds and 1.2 blocks in five games.

[22] He played an instrumental role as his team qualified for the first time in 22 years to the ACB playoffs, where they were eliminated in the quarterfinals by Real Madrid.

The Spanish basketball magazine Gigantes del Basket awarded Antetokounmpo with their 2017 "Top 5 Trophy", which goes to the Liga ACB "Most Spectacular Player of the Year".

On February 17, 2019, he won the Greek Cup's 2019 Grand Final, after Panathinaikos defeated PAOK, by a score of 79–73 [27] in the title game, which was held in Heraklion Indoor Sports Arena, on Crete.

[31] On April 10, 2022, he recorded a career-high 27 points, alongside five rebounds, two assists and a block, in a 133–115 loss to the Cleveland Cavaliers.

[34] A clip of him performing a "Shammgod" move went viral on social media during a game against the Charlotte Hornets on February 10, 2024.

[37] On May 3, 2016, Antetokounmpo was named in the senior men's Nigerian national team training camp preliminary list for the 2016 Rio Olympics.

[44] At the main 2019 FIBA World Cup tournament, he contributed 6.0 points and 1.4 rebounds per game to Greece's national team.

Alex, who graduated from Dominican High School, also went on to play professional basketball in the NBA G League and in Europe.