A house of prayer was built in Itäsalmi (Östersundom) at the end of the 17th century. It was called a chapel as of the 18th century, even though Itäsalmi was never a chapel parish. The exact date of the building of the prayer house is not known. The first mention of the chapel can be found at a winter court in 1690, and it is also visible on a map created the same year. The chapel was built to make the journey to church easier for people living on the coast and in the archipelago.

At the end of the 17th century, the members of the Östersundom chapel included Itäsalmi, Granö, Talosaari, Gumböle and Kärr of Sipoo and Puotila, Vuosaari, Mellunkylä, Länsisalmi, Westerkulla manor, Hakunila and Sotunki of the parish of Helsinki: that is, the same villages which administratively were part of Sipoo at the time. Therefore, the Helsinki parish (Vantaa) and the Sipoo parish carried out the service in the chapel in turn until the 1980s, after which the services became the responsibility of the Sipoo parishes.

The chapel suffered serious damage during the Greater Wrath (1713–1721), and after the Lesser Wrath (1741–1743) it was ready to be demolished. The walls had rotted and the Russian navy had damaged the windows and the interior. The construction of a new chapel in place of the old one started in 1753 and it was dedicated in November 1754. The chapel was thoroughly renovated in 1895. For example, the bell tower was rebuilt, the tower was made narrower and it was given a pointed roof. Central heating was installed in 1912 and electric lights in 1948. The organ was purchased in 1969. In 2003, the chapel was painted inside and the electrical fittings were renewed. The same year, the chapel was renamed Östersundom church.

The altarpiece's Jeesus tyynnyttää myrskyn (Jesus quietens storm) was painted by artist, Hjördis Nyberg, in 1934. The votive painting on the left wall, with an unusual motif, depicts Gustav II Adolf and Charles XII of Sweden at the foot of the cross of Christ. The engraving in ink on the gallery rails, depicting the life of Jesus, was made by Georg Christopher Killian from Augsburg in the latter part of the 18th century, after the motifs of Rubens and Marches. The movables and textiles of the church are mostly donations.

In the Östersundom churchyard lies the tomb of Hanna Hagbom, a school teacher who acted as voluntary organist of the chapel in the early 1900s. She is also known for the melody, Seiskarin kaunis Siiri (Seiskari's fair Siiri).

As of the beginning of 2009, the Östersundom church was transferred to the Mikael parish of Helsinki as part of the Sipoo area incorporation. At the same time, it became the oldest church of Helsinki.

Celebrations at the church

Members of the church can organise a baptism, a wedding or a funeral free of charge in the church.

The Östersundom church has no festive facilities. The Östersundom church seats 250.