Joseph Widmer (15 August 1779 – 10 December 1844) was a Swiss Catholic theologian.
Widmer studied philosophy at Lucerne, and theology at Landshut (1802-4) under Johann Michael Sailer and Patrick Benedict Zimmer, the former exercising a great and abiding influence over him.
After ordination, Widmer was appointed professor of philosophy in 1804, and of moral and pastoral theology in 1819 at the lyceum of Lucerne.
In connection with Joseph Heinrich Aloysius Gügler, Widmer opposed the teachings of Ignaz Heinrich von Wessenberg, and contributed to a Swiss Catholic revival.
Among Widmer's writings are: He edited the works of Sailer (Sulzbach, 1830–46), of Franz Geiger (Fluelen, 1823–39), and Gügler (Lucerne, 1828–40).