McSwain is an unincorporated community and census-designated place (CDP) in Merced County, California, United States.

McSwain is in central Merced County and is bordered to the north by the city of Atwater.

California State Route 99 forms the northern boundary of the community.

Merced, the county seat, is 5 miles (8 km) to the east via State Route 140, which also leads west 25 miles (40 km) to Gustine.

According to the United States Census Bureau, the McSwain CDP covers an area of 6.0 square miles (15.5 km2), all of it land.