Perošević started his career playing at youth level for his hometown club Osijek with whom he had signed a scholarship contract in February 2010. He made his debut for the first team as a late substitute in a 2–0 win against Cibalia on 13 May 2010 in the last round of 2009–10 season. After injuries kept him out of action for a year, he returned for the second part of the 2011–12 season. He scored his first goal in Prva HNL in a 2–1 defeat against Cibalia on 11 March 2012, converting a first-half penalty. He finished the season as Osijek's top league goalscorer with seven goals.