This year's Lucia is 21 year-old Anna-Kajsa Edström from the west coast town of Jakobstad. She is being crowned by Helsinki Mayor Jan Vapaavuori.
After the crowning she will emerge from the church and descend its massive steps to Senate Square. She and her entourage will then lead a procession through the city, as tens of thousands people gather in the square for the spectacle.
This year marks the 61st Lucia procession in Helsinki. Each year's Lucia is chosen by public vote as a charity fund-raising scheme, and then works for several weeks visiting hospitals, retirement homes and schools and other facilities.
The Swedish-language event can be watched via the Yle Areena site.