Knutwil is a municipality in the district of Sursee in the Canton of Lucerne in Switzerland .

Knutwil is first mentioned in the early 12th Century as Gnuthwilare. In 1245 it was mentioned as Knutwile.

Knutwil has an area of 9.8 km2 (3.8 sq mi). Of this area, 69% is used for agricultural purposes, while 20% is forested. Of the rest of the land, 10.7% is settled (buildings or roads) and the remainder (0.2%) is non-productive (rivers, glaciers or mountains).