"The greatness of countries will no longer be measured by their economies alone. The greatness of countries will be measured by the possibilities given to freedom of religion," Gormez said at the opening ceremony, also attended by the Grand Mufti of Russia Rawil Gaynetdin.
Gormez said Kostroma boasted a thousand years of experience of religious freedom as it has been home to numerous different beliefs.
The construction of the Kostroma Central Mosque began in 2003.
The Turkey Diyanet Foundation, the Religious Affairs Directorate and the mufti of Tarsus district -- located in Mersin in southern Turkey -- financially supported the project in the city where nearly 25,000 Muslim people live.