John Forrest National Park, Nature reserve in City of Swan, Australia.

John Forrest National Park is a nature reserve situated in the Darling Scarp region featuring eucalyptus woodlands, seasonal waterfalls, and diverse wildlife throughout its landscape. The park provides walking trails of varying lengths, picnic facilities, barbecue areas, and a nature playground for visitors.

The land was reserved for conservation and recreation in 1898 and named Greenmount National Park two years later, when it became Western Australia's first national park. It kept that name into the late 1930s; the change to John Forrest came only in 1947, honouring the state's first Premier. The Eastern Railway, built through the park in the 1890s, carried excursion trains until the line closed in 1966.

The park's name honours Sir John Forrest, Western Australia's first Premier, from 1947; before that it was Greenmount National Park. The old railway alignment through the park is now the John Forrest Heritage Trail, and the former National Park station site dates from 1936. The wildflower tavern opened in 1978 and closed in 2022.

All walking trails start from the main picnic area, where barbecue and toilet facilities are provided. Routes range from short walks to longer options such as the John Forrest Heritage Trail, Glen Brook Walk Trail and Eagle's View Walk Trail. Parts of the park are also open to horse riders and mountain bikes.

The park's old railway alignment, including the Swan View Tunnel, is now the John Forrest Heritage Trail, vested in the Mundaring Shire Council. The line closed in 1966 when the Avon Valley route opened, and the formation became a walking route.