The St. John's Church gallery organ was built in 1891 by the world-famous German firm E.F. Walcker & Cie in Ludwigsburg. The instrument represented the latest in organ building - pipe pneumatics. When new, the organ was the largest in Finland with 61 voices. The church's first organist, Oskar Merikanto, had the organ enlarged in 1921. After a few less successful rebuilds in 1937 and 1956, also by Walcker, the organ was restored in 2004-05 by Christian Scheffler Orgelwerkstatt in Germany. The organ now has 66 voices and a total of 4036 pipes.

The English-style choir organ was built by Urkurakentamo Veikko Virtanen Oy in Espoo and was completed in 2018. The organ has 9 voices and a movable console. The façade pipes are marbled and painted in the same colors as the original interior of the church. The church got its current color scheme after the overpainting in 1913.

E.F.Walcker & Cie
Founded in 1780, it is known for building and restoring pipe organs. The company has contributed to the development of organ building and created significant organs worldwide.