Delaware Route 23 (DE 23) is a 14.76-mile-long (23.75 km) state highway in Sussex County, Delaware. Its southern terminus is at Massey's Landing in Long Neck, near the confluence of Rehoboth Bay and Indian River Bay and its northern terminus is at the Five Points intersection in Nassau, where it ends at U.S. Route 9 (US 9), DE 1, and DE 404. From the southern terminus, the route runs west through residential areas of Long Neck before heading north through rural areas with some development. DE 23 is concurrent with DE 5 between the DE 24 intersection in Long Neck and Fairmount. It is also concurrent with DE 24 Alternate between Hollymount and the DE 1D intersection in Five Points. The road was designated as part of DE 22 south of Fairmount for a short time in the 1930s, with DE 5 designated along the stretch between DE 24 and Fairmount by 1938; the remainder of the road was unnumbered. The road was fully paved by 1970. The DE 23 designation was assigned by 1994.

Sussex County is located in the southern part of the U.S. state of Delaware, on the Delmarva Peninsula. As of the 2020 census, the population was 237,378, making it the state's second most populated county only behind New Castle and ahead of Kent. The county seat is Georgetown.