The 26-year-old custodian started his professional career in 2015 with Tehran-based Paykan before joining Sepahan in 2018.
Niazmand is also a member of the national team, usually a third choice after Alireza Beiranvand and Amir Abedzadeh.
The fee of his contract with the Primeira Liga side is not revealed but it is reported that a release clause worth €10 million has been put into the deal.
The transfer comes as Alireza Beiranvand has also joined Portugal’s Boavista on loan from Antwerp. Amir Abedzadeh who was playing in Portugal in recent years has opted for a move to Spain this season. Now, all goalkeepers of the national Iranian team are playing in Europe which can also raise hopes for Dragan Skocic’s teams in the World Cup qualifiers.
MAH