Upper Hutt is 30 km north-east of Wellington.

While the main areas of development lie along the Hutt River valley floor, the city extends to the top of the Rimutaka saddle to the north-east and into the Akatarawa Valley and rough hill-country of the Akatarawa ranges to the north and north-west, almost reaching the Kapiti Coast close to Paekakariki.

Centred on the upper (northern) valley of the Hutt River, which flows north-east to south-west on its way to Wellington harbour, it widens briefly into a 2500-m-wide floodplain between the Rimutaka and Akatarawa Ranges before constricting nine kilometres further downstream at the Taita Gorge, which separates Upper Hutt from its neighbour, Lower Hutt.

The city's main urban area is on this plain. A smaller flood plain lies upstream, above the Kaitoke Gorge, but there is little development on it.