Westby is a city in Vernon County, Wisconsin, United States. The population was 2,045 at the 2000 census.
Westby was named after general store owner and Civil War Union soldier Ole T. Westby of Biri, Norway, where many of the city's Norwegian-American settlers originated. The Coon Prairie Lutheran Church in Westby was begun in 1851.
Westby is located at 43°39′14″N 90°51′33″W / 43.65389°N 90.85917°W / 43.65389; -90.85917 (43.653861, -90.859034), at the headwaters of the Bad Axe River.