Whitby, a large suburb of Porirua City, New Zealand, located along much of the southern shore of the Pauatahanui Inlet of Porirua Harbour was comprehensively planned in the 1960s (when still in Hutt County) and it has been continuously developed since, with current landscaping and expansion in the hills behind the eastern part of Whitby to facilitate the future growth of the suburb.

In 1967 some 3,180 acres (1,290 ha) of farmland was purchased by a consortium for a new residential development, to be similar to North American new towns; with a population growing to 16,000 in four "neighbourhoods", each focussed on a primary school.

The consortium developed a village centre and a golf course, and operated a commuter bus service from 1 February 1973.

The original area was part of the Horokiri riding of Hutt County, and some of the later land was in Porirua City.

In 1988 the Local Government Commission decided that all of Whitby should come under the Porirua City Council.

The Community Developments Consortium (originally Huapai Properties) had partners Fletcher Mainline, Jubilee Investments (part of the Todd Group) and the National Mutual Life Association.

Before the 2023 census, Whitby had a smaller boundary, covering 6.45 km2 (2.49 sq mi).

Whitby Collegiate is a co-educational private secondary school for Year 7 to 13 students,[17] with a roll of 320 as of November 2024.

The sale of Marsden Whitby to Fiso Investment Group Ltd was finalised on 10 December 2019.