Fallston is a census-designated place (CDP) in Harford County, Maryland, United States.

[3] It is bordered to the south by Baltimore County and to the northeast by the Bel Air North CDP.

[4] Maryland Route 152 is the main road through Fallston, leading southeast 6 miles (10 km) to Interstate 95 at Exit 74 and northwest 7 miles (11 km) to Maryland Route 146 near Jarrettsville.

Maryland Route 165 passes through the west side of the Fallston CDP, crossing MD 152 at Upper Crossroads, and leads north 4 miles (6 km) to Jarrettsville and south four miles to Baldwin in Baltimore County.

[2] Bon Air, Little Falls Meetinghouse and Rockdale are listed on the National Register of Historic Places.