Paul Okon-Engstler was born in Ostend, Belgium, on 24 January 2005, the son of the former Australia captain Paul Okon, who was then working in Belgian football. He qualifies for Australia and Italy as well and came through the youth ranks at Club Brugge before joining Benfica's academy in 2022.

A left-footed defensive or central midfielder standing 1.86 m, he progressed through the under-19 and under-23 sides and wore the number 72. He was promoted to the Benfica B squad for 2024/25, making eight appearances in the Liga Portugal 2, and did not play for the first team.

Okon-Engstler left in July 2025 for Sydney FC, where a strong first A-League season earned him a move to 1. FC Köln in Germany in July 2026. He is a full Australia international and played for the country at the 2023 Under-20 World Cup.