Ranier is a city in Koochiching County, Minnesota, United States. The population was 145 at the 2010 census.
According to the United States Census Bureau, the city has a total area of 0.2 square miles (0.4 km²), all of it land.
As of the census of 2000, there were 188 people, 76 households, and 50 families residing in the city. The population density was 1,268.1 people per square mile (483.9/km²). There were 88 housing units at an average density of 593.6 per square mile (226.5/km²). The racial makeup of the city was 97.87% White, 1.06% Native American, and 1.06% from two or more races.