After representing Charlton Athletic from U9s up until U16s, and a season at Fisher Athletic, Erhun signed for Manisaspor at the age of 16, who were in the Turkish Super League at the time. He received a scholarship place at Manisaspor and enjoyed two great seasons where he played regularly for the reserve team as their number 10. The success Erhun enjoyed caught the eye of Sivasspor, a club much bigger and positioned higher in the league than Manisaspor, where he earned his first professional contract at the age of 18. In 2011, Erhun joined Anadolu Uskudar where he made 35 senior team league appearances and scored 5 goals.
At the end of the 2011-12 season, Erhun returned to England to join Isthmian League side Dulwich Hamlet. After enjoying two wonderful seasons with Dulwich Hamlet where he scored 61 goals in 97 appearances from midfield and helped them become Ryman South Champions in the 2012-13 season, Erhun got his move to the English Football League with Peterborough United.
Erhun enjoyed 2 successful seasons with Peterborough United where he scored 6 and assisted 6 goals in 30 league appearances in the 2015-16 season and subsequently signed for Walsall after the expiration of his contract.
Erhun also had two very successful seasons as a Walsall player where he scored 30 goals and got 12 assists in 86 league appearances from the 2016-17 and 2017-18 seasons. This record earned him the position as Walsall’s top goal scorer during his time there, as well as Sky Bet League One’s sixth top goal scorer after both seasons with Walsall. Furthermore, he was twice named in the EFL Team of the Season for League One and has earned two Sky Bet League One Goal of the Month awards.
After his two successful seasons with Walsall in Sky Bet League One, Erhun was signed by Bolton Wanderers in summer 2018.