Papapetrou, who is considered to be one of the most talented Greek players that was born in the 1994 age class, along with players like Giannis Antetokounmpo and Lefteris Bochoridis, began his basketball playing career with the youth teams of the Ilysiakos club in Athens, Greece. He played for 5 seasons in Greek junior competitions with Ilysiakos. He then spent his junior and senior years of high school, playing basketball at the Florida Air Academy, in Melbourne, Florida.
Papapetrou's professional career began with the Greek League team Olympiacos in 2013, when he signed a 5-year deal with Olympiacos, in late August 2013, which was his first pro deal.[2][3] The contract was said to be worth $2 million net income.[4] The contract included an NBA buyout option after the contract's third season.[5][6]
On July 8, 2018, Papapetrou declined Olympiacos's renewal proposal and became a free agent. Two days later, he signed with Olympiacos' arch-rivals, Panathinaikos, on a three-year deal.[8]
On February 17, 2019, he won his first title with Panathinaikos, after beating PAOK[9] in the 2019 Greek Cup Final, which was held at Heraklion Indoor Sports Arena. Papapetrou had 10 points, 6 rebounds, 2 assists, 2 steals, and 2 blocks in that game. Four months later, Papapetrou was crowned Greek Basket League champion, after Panathinaikos swept Promitheas Patras in the league's finals.[10]
Prior to the 2020–21 season, Papapetrou became the team's captain after the departure of Nick Calathes. He averaged 12.1 points and 4.1 rebounds per game. On July 11, 2021, Papapetrou officially renewed his contract with the Greek club for an additional two years.[11]
On July 15, 2022, Papapetrou parted ways with Panathinaikos after four seasons together.
Partizan
On July 19, 2022, Papapetrou signed a two-year contract with Serbian powerhouse Partizan, under coach Željko Obradović. During the 2022–23 season, Partizan was eliminated from Real Madrid in a tight 3-2 playoffs series. In 38 EuroLeague games, Papapetrou averaged 5.4 points and 2.3 rebounds in 20 minutes per contest.
Partizan ended the 2022–23 season by lifting the ABA League championship trophy, after a victorious 3–2 series against Crvena zvezda in the finals.[12]
On July 12, 2023, Papapetrou amicably parted ways with the Serbian powerhouse.[13]
Return to Panathinaikos
On July 12, 2023, Papapetrou made his return to Panathinaikos, signing a two-year contract.[14]