The 28-year-old striker has joined the English side on an 18-month contract for an undisclosed fee.
At club level, Ansarifard spent seven years in the Iranian league before signing for Spanish club Osasuna, where he spent a single season ahead of a move to Greece.
In the recent 2018 FIFA World Cup Russia, he scored a late equalizer against Portugal in the group stage.
Ansarifard has 66 caps, having scored 17 goals for the Iran national team.
His countryman Ashkan Dejagah, who currently plays at Tractor Sazi, was a member of Nottingham Forrest last season.