Joseph Ahrens (1904 - 1997) was a German composer and organist.
Ahrens studied in Berlin from 1925 to 1928 with Alfred Sittard, Max Seiffert, and Wilhelm Middelschulte. Between 1931 and 1940 Ahrens was the organist for the Berliner Philharmoniker, simultaneously serving as the organist for the Cathedral of St. Hedwig after 1934. From 1945 to 1957 he was organist at the Salvatorkirche in Berlin-Wilmersdorf. Taking a professorship in church music at the Berlin Hochschule für Musik in 1945, he remained there until 1969, serving as deputy director from 1954 to 1958.
Ahrens was a noted organ improviser. His compositions often combined elements of prior liturgical music styles (such as Gregorian chant) with modern techniques like dodecaphony. A large portion of his output is written for the Catholic Church.
His daughter is the organist Sieglinde Ahrens.
The cycle "Advent" comes from "Das heilige Jahr", which was composed between 1948 and 1950.