Dutch organist and composer, one of the principal figures in the development of organ music before J.S. Bach.

Sweelinck succeeded his father as organist of the Oude Kerk (Old Church), Amsterdam, in about 1580 and remained in this post until his death. Apparently he never left the Low Countries and travelled only to Rotterdam and Antwerp. Although he composed much sacred and secular vocal music in the polyphonic traditions of France and the Netherlands (including the Chansons, the Cantiones sacrae, and settings of the Psalms), Sweelinck was chiefly known as an organist and keyboard composer. His keyboard music includes chorale variations, toccatas and fantasias showing the influence of the Venetian organ school, and sets of variations on secular tunes.

Sweelinck's fantasias are among the first organ fugues in which a single theme is subjected to augmentation, diminution, and changes of rhythm and combined with counter themes. His secular variations drew upon popular tunes of several European countries; an example is the set of variations on ‘Mein Junges Leben hat ein End'.

It is possible that Sweelinck met the English composers John Bull and Peter Philips during their visits to the Low Countries; Bull's ‘Fantasia on a Theme of Sweelinck’ was the tribute of one keyboard virtuoso to another. Sweelinck's keyboard playing was widely known. His organ pupils included the German composers Samuel Scheidt and Heinrich Scheidemann; Scheidemann's pupil J.A. Reinken handed on this tradition of organ playing to the Danish organist Dietrich Buxtehude. Many outstanding organists of the following generation, particularly in northern Germany, were pupils of Sweelinck; Handel and Bach were influenced by this northern German school of organ playing.