Previously a member of Leyton Orient’s academy, and club Youth Team Player of the Year, Papadopoulos signed his first professional contract with the club in May 2021.
Prior to his professional contract being signed, Papadopoulos went on a work experience loan at Harlow Town in October 2020, making four appearances in total before the early curtailment of the season in December, due to the COVID-19 pandemic.
Papadopoulos made his senior debut for Orient in the EFL Trophy at home to Southampton U21 on 14 September 2021. He scored the winning goal in the 82nd minute as Orient won 1–0. He then started in Orient’s next two matches in the tournament, the 4–0 win at Crawley Town on 5 October, and the 1–0 win over Charlton Athletic on 9 November, in which he was sent off. Papadopoulos was released at the end of the 2021–22 season.
On 27 July 2022, Papadopoulos signed for National League South club Welling United