Waldo is a village in Sheboygan County, Wisconsin, United States, along the Onion River. The population was 450 at the 2000 census. It is included in the Sheboygan, Wisconsin Metropolitan Statistical Area.
The village was originally established as Lyndon Station when the Milwaukee & Northern Railroad laid their tracks through in 1871. The village was plated in 1873 by N.C.Harmon. When it was discovered that there already was an existing Lyndon Station elsewhere in Wisconsin, it was decided to rename the village after O.H.Waldo, a prominent Milwaukee attorney and then president of the railroad.
In 1877 the Post Office (Est. 1849) for the Onion River settlement (Est. 1844), one mile east was closed and Onion River also became part of Waldo. In 1923 Waldo became an incorporated village and Onion River ceased to exist. The open area between has since been built up.