Maryland Route 285 (MD 285) is a state highway in the U.S. state of Maryland. The state highway runs 2.43 miles (3.91 km) from MD 213 east to the Delaware state line within Chesapeake City. MD 285 roughly parallels the north side of the Chesapeake and Delaware Canal in southern Cecil County. The state highway was paved along Biddle Street from Lock Street, then part of U.S. Route 213 (now MD 213), east to the state line around 1930. When US 213 was moved to the Chesapeake City Bridge in the late 1940s, MD 285 was extended along Lock Street to reconnect with US 213.

MD 285 begins at an intersection with MD 213 (Augustine Herman Highway) just north of the Chesapeake City Bridge. The state highway, which heads east as two-lane Lock Street, curves to the south at the intersection with county-maintained Hemphill Street. At the intersection with MD 284 (Hemphill Street), MD 285 curves to the southwest, following Lock Street into the town of Chesapeake City to its intersection with Biddle Street. MD 285 turns east onto Biddle Street while a stub of Lock Street continues south to the edge of the canal as unsigned MD 537B. The state highway passes through a residential section of the north side of the town, meeting the other end of MD 284. MD 285 runs through an S-curve before leaving the town limits. The state highway passes through a mix of farmland and scattered residences as it parallels the north side of the canal. At Knights Corner Road, MD 285 curves northeast away from the canal to its eastern terminus at the Delaware state line. The roadway continues east as Chesapeake City Road.

MD 285 was constructed in three sections. The portion of Lock Street between county-maintained Hemphill Street and the northern junction with MD 284 was part of the original Cecilton–Elkton highway passing through Chesapeake City that was designated for improvement by the Maryland State Roads Commission in 1909. This segment of state road was paved in 1914. Following the expansion and straightening of the Chesapeake and Delaware Canal in the 1920s, the portion of Lock Street from the northern junction with MD 284 to Biddle Street was constructed as the approach to a vertical lift bridge constructed by the U.S. Army Corps of Engineers, connecting Lock Street on the north side with George Street on the south side of the town in 1926. This new alignment became part of US 213 when the federal highway was marked through southern Cecil County around 1927.

Biddle Street was paved from US 213 to the Delaware state line and designated MD 285 around 1930. The vertical lift bridge used by US 213 to cross the canal was destroyed by the tanker Franz Klasen on July 28, 1942. A ferry was established to carry traffic across the canal until the completion of a new bridge. The Chesapeake City Bridge was completed in 1948 along with new approach roads; US 213 was moved to the new bridge and approach roads and MD 285 was extended north on Lock Street to its present western terminus at US 213.

The entire route is in Cecil County.