Oronoco is a city in Olmsted County, Minnesota, United States, along the Middle Fork of the Zumbro River. The population was 883 at the 2000 census. The city was named by early settler Dr. Hector Galloway for the similarly spelled Orinoco, a large river in South America. A village was founded in 1854 and platted in 1855. The village incorporated as a city on March 6, 1968. Oronoco Township, which is adjacent on three sides, was organized in 1858.