Mohammadi has signed a three-year contract with the Belgian football club.
The 25-year-old player has collected 30 caps for the Iran national football team.
Mohammadi represented Iran at the 2018 World Cup in Russia. He is a versatile player and is capable of playing in left and right back.
His contract expired with Russian football club Akhmat Grozny this summer.
Newcastle and Celtic were the teams who had shown interest in signing the Iranian player.