The 38-year-old has penned a one-year deal with Esteghlal.
A youth product of Real Madrid, where he primarily served as a backup, Adan has spent most of his career with Betis. He has also played for Atlético Madrid, for whom he signed in 2018, and has accumulated a total of 129 La Liga appearances across these clubs.
Esteghlal, under the management of Portuguese coach Ricardo Sá Pinto, has recently parted ways with Hossein Hosseini.