The London Borough of Waltham Forest () is a London borough in north-east London, England. Its population is estimated to be 276,983 in 2019. It borders five other London boroughs: Enfield to the north-west, Haringey to the west, Hackney to the south-west, Newham to the south-east and Redbridge to the east, as well as the non-metropolitan county of Essex to the north.
The borough was formed in 1965 from the merger of the municipal boroughs of Leyton, Walthamstow and Chingford; it took its name from Waltham Forest – an institution which managed deer in south-west Essex.
Epping Forest is a remainder of the former Waltham Forest and forms the eastern and northern fringe of the borough. The River Lea lies to the west where its associated marshes and parkland form a green corridor which, along the reservoir-lined reaches, separates north and east London, and is the historic border between Middlesex, and Essex
The north and south of the borough, split by the North Circular Road, contrast markedly in terms of demographic and socio-economic indicators; with urban districts in the south having inner-city characteristics, and the more affluent suburban areas to the north having better access to open spaces, parks, and playing fields. Chingford in the north, Walthamstow in the middle, and both Leyton and Leytonstone in the south are the four urban centres of the borough.
Waltham Forest was one of the host boroughs of the London Olympics in 2012, with the Lee Valley Hockey and Tennis Centre and part of the Queen Elizabeth Olympic Park providing an ongoing legacy in the UK and London.