Rahmati has penned a two-year contract for an undisclosed fee, however reports put the transfer fee at about $700,000.
Rahmati won the Iranian league titles twice along with Sepahan of Isfahan.
The 28-year old keeper was a member of Esteghlal football team from 2005 to 2007.
Rahmati has played for Iran football team 58 times.
Sepahan defender Jalal Hosseini has also agreed to join Esteghlal. He will join the Tehran giant on a one-year contract.
