Duncan Ranch Colony is a Hutterite community and census-designated place (CDP) in Wheatland County, Montana, United States. It is in the west-central part of the county, on the south side of U.S. Route 12, west of Harlowton, the county seat, and east of Twodot. The Musselshell River flows eastward through the colony. As of the 2020 census, Duncan Ranch Colony had a population of 7.
The community was first listed as a CDP prior to the 2020 census.
It is zoned to Harlowton Public Schools.