The Lake Ontario State Parkway is a 35.05-mile (56.41 km) limited-access parkway along the southern shore of Lake Ontario in Western New York in the United States. The western end of the highway is at a partial interchange within Lakeside Beach State Park in Carlton, Orleans County. Its eastern terminus is at an intersection with Lake Avenue in the Charlotte neighborhood of the Monroe County city of Rochester. The parkway is internally designated by the New York State Department of Transportation (NYSDOT) as New York State Route 947A (NY 947A), an unsigned reference route. A short, 0.55-mile (0.89 km) connector between the west end of the parkway and NY 18 is unsigned New York State Route 948A.

The majority of parkways in the US state of New York are part of a statewide parkway system owned by several public and private agencies but mostly maintained by the New York State Department of Transportation (NYSDOT). A handful of other roads in the Hudson Valley and on Long Island are also known as parkways but are not part of the state system. The roads of the state parkway system were among the first expressways to be constructed. These highways were not divided and allowed no driveway cuts, but did have intersections for some of the streets they crossed. A small section of the privately financed Long Island Motor Parkway was the first expressway to begin operation as a toll road and the first highway to use bridges and overpasses to eliminate intersections.