[3] It is located adjacent to Clendon Park and Manurewa, some 25 kilometres (16 mi) southeast of Auckland city centre, and is sited on a peninsula between the southeastern shore of the Manukau Harbour and that Harbour's Pahurehure Inlet.

Weymouth is connected to the Auckland Southern Motorway via Mahia Road, an arterial route which cuts across the suburb's northeastern corner.

The traditional name for the Weymouth area is Waimāhia, meaning "the muffled waters", referring to how sounds of the Manukau Harbour would sound distorted in unexpected ways in the area.

In order to avoid a lengthy detour via Drury, this bridged the Papakura Channel between Weymouth and Karaka, providing travellers with a direct path to Waiuku in the south.

Weymouth became a well-liked vacation spot and the location of an annual regatta around the beginning of the 20th century.

Weymouth had large amounts of Chinese immigration starting in the 1920s who set up market gardens using the fertile alluvial soil.

A defined boundary between the two suburbs was introduced by the Weymouth Residents & Ratepayers Association in 1990.

The results were 22.9% European (Pākehā); 29.3% Māori; 46.8% Pasifika; 22.5% Asian; 2.7% Middle Eastern, Latin American and African New Zealanders (MELAA); and 0.9% other, which includes people giving their ethnicity as "New Zealander".