Onaero is a settlement in northern Taranaki, in the North Island of New Zealand. It is located on State Highway 3 close to the shore of the North Taranaki Bight, 15 kilometres (9.3 mi) east of Waitara. Onaero was the site of the No. 2 Company Redoubt, a British military installation created during the Second Taranaki War by soldiers from the Tikorangi Redoubt in 1865, however it was abandoned several months later.

Onaero Beach is defined by Statistics New Zealand as a rural settlement. It covers 0.15 km (0.058 sq mi) and had an estimated population of 70 as of June 2023, with a population density of 467 people per km. It is part of the wider Tikorangi statistical area, which covers 167.79 km (64.78 sq mi).

Historical population

Year	Pop.	±% p.a.
2006	75	—
2013	78	+0.56%
2018	75	−0.78%
Source:

Onaero had a population of 75 at the 2018 New Zealand census, a decrease of 3 people (−3.8%) since the 2013 census, and unchanged since the 2006 census. There were 39 households, comprising 39 males and 36 females, giving a sex ratio of 1.08 males per female. The median age was 57.2 years (compared with 37.4 years nationally), with 6 people (8.0%) aged under 15 years, 6 (8.0%) aged 15 to 29, 39 (52.0%) aged 30 to 64, and 21 (28.0%) aged 65 or older.

Ethnicities were 88.0% European/Pākehā, 16.0% Māori, and 4.0% Pacific peoples. People may identify with more than one ethnicity.

Although some people chose not to answer the census's question about religious affiliation, 52.0% had no religion, and 36.0% were Christian.

Of those at least 15 years old, 18 (26.1%) people had a bachelor's or higher degree, and 6 (8.7%) people had no formal qualifications. The median income was $39,600, compared with $31,800 nationally. 12 people (17.4%) earned over $70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 33 (47.8%) people were employed full-time, and 15 (21.7%) were part-time.

• Whilst strictly not an historical work (in the sense of being a published book/monograph), the papers of Dick Purdie Jonas (held at "Puke Ariki". Archived from the original on 20 June 2008. in New Plymouth) provide a wealth of historical, archaeological, and anthropological information about this region. See "Jonas, Dick Purdie (ARC2002-166)". Archived from the original on 14 October 2008. Retrieved 26 January 2008.

• Bristow, Margaret (1978). Onaero-Mohikatino (i.e. Mohakatino) survey (Report). Stratford, [N.Z.]: Taranaki Catchment Commission.
• Jardine, Edward Handforth (1981). Water and land use: part I, Tikorangi-Motunui district: part II, Onaero Catchment (Report). Stratford, [N.Z.]: Taranaki Catchment Commission.

• Hayward, Bruce W. (1981). Biostratigraphy of Onaero-1 onshore well (Report). Lower Hutt, [N.Z.]: New Zealand Geological Survey, Dept. of Scientific and Industrial Research.

• See "ARC2002-166 (papers of) Jonas, Dick Purdie". Archived from the original on 14 October 2008. Retrieved 26 January 2008.

• For a 1969 map of the scenic reserves within north Taranaki (including the Onaero River, whose estuary forms the setting for the community and its beach resort) see "ARC2005-436 Scenic Reserves". Archived from the original on 14 October 2008. Retrieved 26 January 2008. . This is held at "Puke Ariki". Archived from the original on 20 June 2008. in New Plymouth.