An urban forest is a forest, or a grove of trees, that grow within a city, town or a suburb. In a wider sense, it may include any kind of woody plant vegetation growing in and around human settlements. In urban areas, sections of urban forest and remnant bushland are sometimes fenced or otherwise restricted to protect regenerating vegetation, reduce human disturbance to sensitive habitats, and manage safety risks associated with drainage infrastructure or uneven terrain.

As opposed to a forest park, whose ecosystems are also inherited from wilderness leftovers, urban forests often lack amenities like public bathrooms, paved paths, or sometimes clear borders which are distinct features of parks. Care and management of urban forests is called urban forestry. Urban forests can be privately and publicly owned. Some municipal forests may be located outside of the town or city to which they belong.

In many countries there is a growing understanding of the importance of the natural ecology in urban forests. There are numerous projects underway aimed at restoration and preservation of ecosystems, ranging from simple elimination of leaf-raking and elimination of invasive plants to full-blown reintroduction of original species and riparian ecosystems.

Some sources claim that the largest man-made urban forest in the world is located in Johannesburg in South Africa. The city is located in the highveld, a grassland biome typically lacking large numbers of trees, yet Johannesburg is still a very densely wooded city with reportedly 10 million artificially introduced trees and is rated as the city with the eighth highest tree coverage in the world.

Rio de Janeiro is also home to two of the vastest urban forests in the world, one of which is considered by some sources to be the largest one. Tijuca Forest is the most famous. It began as a restoration policy in 1844 to conserve the natural remnants of forest and replant in areas previously cleared for sugar and coffee. Despite the worldwide recognition of Tijuca Forest, another forest in the same city encompasses roughly three times the size of its more prominent neighbor: Pedra Branca State Park occupies 12,500 hectares (30,888 acres) of city land, against Tijuca's 3,953 hectares (9,768 acres). The larger metropolitan area encircles the forests which moderate the humid climate and provide sources of recreation for urban dwellers. Along with seven other smaller full protection conservation units in the city, they form an extensive natural area that contains the Transcarioca Trail, a 180-km footpath.

Sanjay Gandhi National Park in Mumbai, Maharashtra, India is also an example of an urban forest. It covers roughly around 20% area of the city. The forest is filled with many animals freely roaming around. It also has an important cultural site of ancient history situated in it known as the Kanheri caves. Nebraska National Forest is the largest man-made forest in the United States located in the state of Nebraska. It lies in several counties within the state and is a popular destination for campers year-round.

Several cities within the United States have also taken initiative investing in their urban forests to improve the well-being and economies of their communities. Some notable cities among them are Austin, Atlanta, Nashville, New York, Seattle, and Washington, D.C. New York, for example, has taken initiative to combat climate change by planting millions of trees around the city. In Austin, private companies are funding tree-planting campaigns for environmental and energy-saving purposes.

Nashville has an organization known as the Alliance to Conserve Nashville's Highland Rim Forest serving as a catalyst to pool action from across numerous conservation nonprofits that include the Cumberland River Compact, Friends of Beaman Park, and the Tennessee Environmental Council. Nashville contains the largest urban forest within the city limits of any city in the world with a population exceeding 500,000.