Hosseini has joined the Isfahan-based football club on a two-year contract for an undisclosed fee.
The 29-year-old player is reunited with his former coach Amir Ghalenoei in Sepahan.
Sepahan became runner-up in the Iran Professional League (IPL) last season and booked a place in the 2020 AFC Champions League.
Hosseini had also been linked with a move to Tractor Sazi and Esteghlal.