Mousavi officially joined Italian volleyball club Gas Sales Piacenza on Friday from his homeland team Saipa after a long and complex negotiation.
Piacenza is headed by Lorenzo Bernardi, who was a candidate to take charge of Iran volleyball team.
The Italian team is a favorite to win 2020-21 Superlega.
At the club level Mousavi has collected 11 Iranian championships and eight AVC Club Championships in his career.
Mousavi,33, will be a key player of Iran National Team at the 2021 Volleyball Nations League and Olympic Games in Tokyo.