The 23-year-old defensive midfielder has joined the Iranian giant as Omid Ebrahimi’s replacement.
Ebrahimi has recently signed a contract with Al Ahli of Qatar.
Karimi started his playing career in Sepahan in 2012 and joined Dinamo Zagreb in 2016.
He joined Esteghlal’s training camp in Turkey Sunday night.
Esteghlal is preparing for the new season of Iran Professional League as well as two vital matches against Al Sadd of Qatar in the AFC Champions League quarter-final.