Knellsville is an unincorporated community in the Town of Port Washington, Ozaukee County, Wisconsin, United States.

[2][3] Located in the Milwaukee Metropolitan Area on the north side of the intersection of Interstate 43 and Wisconsin Highway 32, Knellsville borders the City of Port Washington's northern municipal limit.

[4] Knellsville is named for William Knell, who settled in the area in the early 1860s[5] and developed the community as a stagecoach stop in the Green Bay Road.

[11] Due to this plan, Knellsville is unique among unincorporated communities in that the town in which it lies has given it a defined border.

Knellsville's western border lies along the Union Pacific railroad tracks, which run parallel to Sauk Creek.