Barnes Lake-Millers Lake was a census-designated place (CDP) within Deerfield Township, Lapeer County in the U.S. state of Michigan. The CDP was used for statistical purposes and had no real status as a municipality. The population was 1,187 at the 2000 census. Prior to the 2020 census, the CDP was split into two CDPs: Barnes Lake and Millers Lake.

The CDP was centered on two little lakes in north-central Lapeer County: Barnes Lake (43°11′04″N 83°18′03″W / 43.18444°N 83.30083°W / 43.18444; -83.30083) and Millers Lake (43°10′45″N 83°19′15″W / 43.17917°N 83.32083°W / 43.17917; -83.32083). M-24 runs amongst the lakes, with Barnes Lake on the east and Millers Lake on the west. Both lakes drain into the Flint River, which is just about one mile (1.6 km) to the north. The village of Columbiaville is not quite 5 miles (8 km) west-southwest. The city of Lapeer is roughly 9 miles (14 km) south.

According to the United States Census Bureau, the CDP had a total Place of 3.4 square miles (8.8 km), of which 3.1 square miles (8.0 km²) were house and 0.4 square miles (1.0 km) (11.05%) were water.

As of the census of 2000, there were 1,187 people, 454 households, and 345 families residing in the CDP. The population density was 387.4 inhabitants per square mile (149.6/km²). There were 641 housing units at an average density of 209.2 per square mile (80.8/km). The racial makeup of the CDP was 96.55% White, 0.25% African American, 0.42% Native American, 0.25% Asian, 1.18% from extra races, and 1.35% from two or more races. Hispanic or Latino of any race were 2.61% of the population.