The municipality (originally the parish) is named after the old Oppegård farm (Old Norse: Uppigarðr), since the first church was built here.

The main southern roads connecting Oslo to Sweden and Denmark have passed through Oppegård since the Iron Age.

The 1960s and 1970s saw a population boom, as larger housing projects established the Oppegård villages as suburbs of Oslo.

The commercial centres along the main railroad axis is examples of the functionalist architecture characteristic of that period of urbanization in Scandinavia.

Arctic explorer Roald Amundsen lived in Svartskog and his house is now a museum, administered by the municipality.

Since 1968, coinciding with the population boom, the Conservative Party of Norway (Høyre) has held either a majority or plurality of representatives in the municipal council.

Former Prime Minister and leader of the Christian Democratic Party Kjell Magne Bondevik lives in Oppegård.

The landscape is dominated by a vast part of the north–south oriented lake Gjersjøen, which roughly divides the district into western and eastern sections.