The cathedral is also used for services by the Porvoo Finnish-speaking parish, which is administratively part of the Diocese of Helsinki. The church first became a cathedral in 1723, when the diocese of Viipuri (Viborg) (now the Diocese of Tampere) moved to Porvoo, after Vyborg was ceded to Russia in the Treaty of Nystad.
The cathedral is also used by the Porvoo Finnish-speaking parish, which belongs administratively to the Diocese of Helsinki. The church became a cathedral in 1723 when the diocese of Viipuri (now Tampere) relocated to Porvoo following Vyborg's ceding to Russia under the Treaty of Nystad.