The heart of the park is the Chacabuco Valley, a biologically important east-west valley that forms a pass over the Andes Mountains and a transition zone between the Patagonian steppe grasslands of Argentinian Patagonia and the southern beech forests of Chilean Patagonia to the west. Parque Patagonia is located between the Lago Jeinimeni National Reserve to the north and the Lago Cochrane National Reserve to the south.
Parque Patagnoia was created by Conservacion Patagonica, a nonprofit incorporated in California and founded in 2000 by Kris Tompkins, to protect Patagonia's wildlands and ecosystems.  Parque Patagonia has an infrastructure of trails, campgrounds, and a visitor center.
On January 29, 2018, Chilean President Michelle Bachelet and Kris Tompkins, President and CEO of Tompkins Conservation, signed a decree creating 5 national parks, one of which is Patagonia National Park. Parque Patagonia will be gifted to the Chilean state and then combined with Lago Jeinimeni National Reserve, Lago Cochrane National Reserve, and other additional lands to create Patagonia National Park, with a combined area of 260,000 hectares (640,000 acres).    
Originally one of the region’s largest sheep ranches, Estancia Valle Chacabuco has changed hands many times over the past century.  British explorer Lucas Bridges established the area as ranchland in 1908, but through the efforts of the Eduardo Frei Montalva administration to redistribute wealth, the land was expropriated and divided between several local families in 1964. The land was reclaimed once again, this time by the Augusto Pinochet administration, and then sold to Belgian landowner Francoise de Smet in 1980.
Kris and Doug Tompkins   first visited the Chacabuco Valley in 1995. CONAF (Chile’s National Forest Corporation) had listed the Chacabuco Valley as a top conservation priority for over 30 years. After two decades of declining profits, in 2004, and with the help of Tompkins Conservation, Conservacion Patagonica purchased the 70,600-hectare (174,500-acre) Estancia Valle Chacabuco from de Smet and set about selling off livestock, taking down fences, restoring grasslands and forests, and developing species-specific restoration programs.   As the park was re-wilded a public-access infrastructure was built that included trails, campgrounds, lodging and employee housing. Since acquiring the estancia, smaller land acquisitions have expanded Parque Patagonia to nearly 81,000 hectares (200,000 acres). 
Located in the transition zone between the arid steppe of Argentine Patagonia and the temperate southern beech forests of Chilean Patagonia, Parque Patagonia encompasses an array of ecosystems including Grassland, Riparian forest, and Wetland.   
The dry steppe grasslands of Argentine Patagonia are characterized by minimal rainfall, cold, dry winds, and sandy soil. The Andean Mountains block moisture from flowing west, creating this arid area region. A number of plants have been able to adapt to this harsh environment, including shrubs like calafate, quilembay and yaoyín, and tuft grasses like flechilla and coirón poa. These grasslands support hardy animals such as the burrowing owl, the gray fox, tuco-tuco, mara, armadillos, various eagle and hawk species, and keystone predators like the puma. A wide range of animals thrive in the more habitable outskirts of the desert and around ephemeral lakes formed from the Andes' runoff, where trees and more nutritious aqueous grasses can grow.
Moving west and climbing the vertical gradient of the Andes Mountains, the park’s flora and fauna changes notably. The landscape begins to transform into forests, which consists mostly of three species of the southern beech (Nothofagus) genus: lenga, ñire, and coiue. Here, rainfall can be very high, generating dense forests, full of nutrients from high leaf litter. These forests host 370 vascular plant genera, which are vital to the survival of the surrounding fauna.  Some significant mammals include the endangered huemul deer, puma, red fox, and various species of bats. The forests of Parque Patagonia also contain a high diversity of bird species including the Andean condor, Magellanic woodpecker, Spectacled Duck, Black-necked swan, pygmy owl, Black-faced ibis, Chilean flamingo, Austral negrito, Southern lapwing and a range of amphibians and reptiles.
Throughout Patagonia, the guanaco,  a large camelid that is a wild relative of the llama, is the most abundant herbivore. It feeds on 75% of all plant species in the Patagonian steppe. The guanaco acts as a keystone species: it prevents domination of grass species, acts as a disperser and fertilizes, and has high reproductive rates  , providing food for local carnivores, especially pumas.
Although the park lies on the eastern side of the Andes, its glacier-fed streams and rivers run toward the Pacific Ocean. Their turquoise blue water is home to substantial populations of native fish such as Perch (Percichthys trucha), pejerrey patagonico (Patagonina hatcheri) and puyen. Atlantic salmon, as well as brook, brown, and rainbow trout, have been introduced to the area.
Visiting the Park
Parque Patagonia is open October through April and only accessible by car. It is south of Coyhaique, Chile and north of Cochrane, Chile. The closest airport is Balmaceda, Chile (BBA). A 300 km drive from Balmaceda on the Carretera Austral is necessary to reach the park. As of March 2018, the Carretera Austral is only paved between Balmaceda and Cerro Castillo, Chile. The remaining portion of the highway to the park is unpaved.
The ranger station in Sector Jeinimeni is easily reachable by car in about 1.5 hours from the town of Chile Chico. It is a 2 to 5 day hike along the Aviles Trail to the Lodge at Valle Chacabuco.
The Lodge at Valle Chacabuco,  at the center of the park, houses the park's main tourist infrastructure, including a lodge, restaurant, visitor center and employee housing. There are also three campgrounds in the park.  
- "Parque Patagonia: Leading a New Generation of Land Conservation". Will Carless. Patagonia, 2015. ISBN 978-1938340475
- "Patagonia Dreaming: Kris Tompkins Works to Build the Best National Park". Bradford Wieners. Bloomberg. April 23, 2014. 
- "With 10 Million Acres in Patagonia, a National Park System is Born". Pascale Bonnefoy. The New York Times. February 19, 2018. 
- "Chile creates five national parks over 10m acres in historic act of conservation". Jonahtan Franklin. The Guardian. January 29, 2018. 
- "Chile Adds 10 Million Acres of Parkland in Historic First". Elizabeth Royte and Michael Greshko. National Geographic. January 29, 2018. 
- "President of Chile and CEO of Tompkins Conservation sign decrees creating 10 million acres of new national parks". Patagon Journal. January 29, 2018. 
- "A History of Valle Chacabuco". Conservacion Patagonica. August 28, 2102. 
- "The Entrepreneur Who Wants to Save Paradise". Diana Saverin. The Atlantic. September 15, 2014. 
- "Patagonia’s controversial new national park". Graeme Green. The Guardian. November 2, 2015. 
- "Restoring the Eco-System in Chilean Patagonia". Lindsey Olander. Travel and Leisure. October 20, 2015. 
- "Remotest Patagonia: Alone With the Wildlife in the Chacabuco Valley". Holly Williams. Independent. October 9, 2015. 
- "4,000 Acres Added to Patagonia Park". Conservacion Patagonica. March 30, 2017. 
- "Grasslands of the World". Edited by J.M. Suttie, S.G. Reynolds and C. Batello. Food and Agriculture Organization of the United Nations. 2005. 
- "Patagonian Steppe". International Union for Conservation of Nature. July 9, 2010.
- "The Andean-Patagonian Forest". Tierras Patagonicas.
- "Plant Evolution and Endemism in Andean South America: An Introduction" Kenneth Young, Carmen Ulloa, James Luteyn, Sandra Knapp. The Botanical Review. May 15, 2002. 
- "Guanaco Fact Sheet". San Diego Zoo. March 2009.  Archived 2015-02-28 at the Wayback Machine
- "Reproduction in South American Camelids". Timothy Smith. Iowa State University. 1985. 
- "The Lodge at Valle Chacabuco". Parque Patagonia. 
- "Getting Lost in Chile’s Brand New National Park". Daniel Duane. Men's Journal. 
- "First Tracks in Chile's New Patagonia Park". Tomás Dinges. Backpacker. November 11, 2014.