Saint John's Church, Gothic parish church in Mechelen, Belgium.

Saint John's Church is a 15th-century Gothic church in Mechelen, built of pale stone. Its square tower, topped by a 55.5-metre spire with four corner pinnacles, stands beside a steep dark roof with a flèche. Inside, a tall pointed-arch vault crossed by thin metal tie rods rises above clustered columns, plain wooden chairs, a carved wooden pulpit and side chapels with statues.

A chapel dedicated to John the Baptist stood here in the 13th century and became a parish church in the same century. It was enlarged with a choir, transept and side aisles in the 14th century, then rebuilt as a full church in the second half of the 15th century. The spire, said to come from the old St. Rumbold's Tower, was consecrated in 1483 by Hendrik van Bergen, bishop of Cambrai. The building was badly damaged by the explosion of the Zandpoort in 1546, and in 1566 iconoclasts plundered the interior.

The church is dedicated to both John the Baptist and John the Evangelist, and its artworks follow that double dedication: Rubens painted the four side panels of the high-altarpiece triptych, contracted on 27 December 1616 and delivered in 1617, with scenes of John on Patmos, John in boiling oil, the beheading of the Baptist and the baptism of Christ. The pulpit and the churchwardens' benches are by Theodoor Verhaegen, the organ case and rear benches by Pieter Valckx.

The church stands in Mechelen's centre, about 20 metres north-west of the Stadsfeestzaal. The 14th-century wall paintings of Saint Christopher and Saint George, found in 2008 behind the organ case on the tower's first floor, can be seen only with a guide. The interior restoration was completed in 2018.

In 2008, the Flemish Institute for Immovable Heritage found two large 14th-century wall paintings behind the organ case on the tower's first floor, showing Saint Christopher and Saint George. They are not fragments but complete works, and can be seen only with a guide.