Born in
Limassol, Kousoulos signed his first professional contract with
Nea Salamina at the age of 18. On 3 July 2018, Kousoulos joined
Omonia on a four-year contract. In August 2020, he renewed his contract until 2024. Kousoulos started the vast majority of Omonia's games in the
2020–21 season, in which he helped his team win the domestic league, and was named Omonia's
vice-captain. He was given the nickname "Machine" by then Omonia coach
Henning Berg. On 20 July 2021, Kousoulos sustained a knee cartilage injury in a
Champions League qualifier against
Dinamo Zagreb, which kept him out of action for the entirety of the
2021–22 season. He made his return on 3 September 2022, coming on as a substitute in a 3–2 home win against
AEK Larnaca in the
Cypriot League. He ended the 2022–23 season as
Cup winner with Omonia. ==Career statistics==