Parks in Greater St. Louis are administered by a variety of state, county, and municipal authorities. The region also is home to Gateway Arch National Park, site of the Gateway Arch, the only National Memorial in the state of Missouri. Among the largest municipal parks is Forest Park, which is and is located in the city of St. Louis, although both Greensfelder County Park and Creve Coeur Park in St. Louis County are larger, at respectively. St. Louis County is also the location of two large state parks, Babler State Park with and Castlewood State Park with . The largest state park in the region is Meramec State Park, located near Sullivan, Missouri, with of parkland.
The city of St. Louis owns and maintains more than one hundred parks, ranging in size from the of Forest Park to less the than of Aboussie Park. Parks are administered by the city of St. Louis Department of Parks, Recreation and Forestry, the National Park Service, or a separate private board, such as Tower Grove Park, which is maintained by a Board of Commissioners but remains city property. Compton Hill Reservoir Park is owned by the city but maintained by the St. Louis Water Division.
The city of St. Louis is also home to several public parks that are owned by other entities. Among these is Baer Plaza, owned and maintained by CVC/Sports Authority, Gateway Arch National Park, owned and maintained by the National Park Service, Kiel Triangle Park, owned by the Bi-State Development Agency, and Luther Ely Smith Park, owned and maintained by the National Park Service.
St. Louis County owns and maintains more than forty parks, including playgrounds and nature preserves. It also operates several recreation centers, the National Museum of Transportation, and the Affton Community Center. In addition to parks owned by St. Louis County, several municipalities in the county also own and maintain their own park systems.
Notable parks maintained by St. Charles County include Indian Camp Creek Park, Kinetic Park, Klondike Park, Quail Ridge Park, and Towne Park. The city of O'Fallon maintains Fort Zumwalt Park.
The Dardenne Creek Blueway is the first in a planned series of kayaking and canoeing routes connecting St. Charles area parks and recreation facilities. The blueway's first stretch links Riverside Landing County Park on the Mississippi River to St. Peters' 370 Lakeside Park and takes up to two hours for a round trip. The next stage opened in the fall of 2022 and linked to St. Peters' Lone Wolff Park to the southwest. Three future phases will connect Jack Gettemeyer Park, O'Fallon Sports Park, and Bluebird Meadow Park for a total of 19 miles (30.6 km) of access along Dardenne Creek. A future route is the Big Creek Blueway, which will connect Indian Camp Creek and Flatwoods parks through Big Creek and the Cuivre River, or about 12.3 miles (19.8 km).
Twelve Missouri state parks are in Greater St. Louis, and the Missouri Department of Natural Resources also operates several state historic sites in the region.