Glenfield is located to the north of the Waitemata Harbour, nine kilometres northwest of the Auckland city centre. The suburb is located in the northern inland part of the North Shore, and is surrounded by the suburbs of Sunnynook, Forrest Hill, Birkenhead, Northcote and is situated close to Takapuna. The northern part of Glenfield is regarded as a separate suburb known as Glenfield North. This latter suburb is sited close to State Highway 1 as it stretches north towards Albany.
Glenfield has two main areas of commerce. One is the former Glenfield Mall and the surrounding shops (this is now predominantly covered by Westfield Glenfield). The other is Wairau Valley, which is a former industrial area that is now a mixture of commercial and industrial properties.
Prior to the opening of the Auckland Harbour Bridge in 1959, Glenfield primarily consisted of farmland. During the 1960s, as access to the area improved, many of the large farm properties were subdivided to provide space for residential development.
On 9 December 1971, in response to fears about commercial sprawl down the length of Glenfield Rd, Glenfield Mall opened. This makes it one of the oldest enclosed malls in the country. It featured a large aviary in the centre of the mall. In 2000, Glenfield Mall was completely redeveloped as Westfield Glenfield, continuing on as popular shopping destination for locals.