The religious leader, understood to be Sheikh Maymoun Zarzour, was found at the Muslim Welfare House in Seven Sisters Road, Finsbury Park, on Friday.
A man was arrested at the scene on suspicion of murder. A post-mortem examination is being arranged.
The Metropolitan Police said it was not believed to be a faith hate crime.
Officers believe the suspect attended the mosque.
A statement on the Muslim Welfare House Trust’s website read: “Our imam has passed away after he led prayer.
