The 22-year-old player has joined the Iranian giant on a three-year contract for an undisclosed fee.
Tariq, who most recently played for Iraqi club Al-Quwa Al-Jawiya, has made 45 appearances for Iraq national football team and scored one goal.
Esteghlal had signed two new players on Tuesday.
The Iranian giant hired Zob Ahan striker Morteza Tabrizi and German midfielder Markus Martin Neumayr.
The Iranian team must strengthen itself since it will face Qatar’s Al Sadd in the AFC Champions League’s quarter-final in late August.