Ōpaki is a small rural settlement in the Masterton District and Wellington Region of New Zealand's North Island.

Opaki railway station is located at Ōpaki. The centre of the village was bypassed in 1938, when a bridge replaced the railway level crossing,^[3] on what is now SH2.^[4]

Ōpaki statistical area covers 35.62 km² (13.75 sq mi).^[1] It had an estimated population of 1,190 as of June 2023,^[2] with a population density of 33 people per km².

Before the 2023 census, the statistical area had a larger boundary, covering 36.04 km² (13.92 sq mi).^[1] Using that boundary, Ōpaki had a population of 1,140 at the 2018 New Zealand census, an increase of 126 people (12.4%) since the 2013 census, and an increase of 288 people (33.8%) since the 2006 census. There were 435 households, comprising 555 males and 582 females, giving a sex ratio of 0.95 males per female. The median age was 49.4 years (compared with 37.4 years nationally), with 201 people (17.6%) aged under 15 years, 132 (11.6%) aged 15 to 29, 567 (49.7%) aged 30 to 64, and 240 (21.1%) aged 65 or older.

Ethnicities were 95.8% European/Pākehā, 8.2% Māori, 0.8% Pasifika, 1.1% Asian, and 1.6% other ethnicities. People may identify with more than one ethnicity.

The percentage of people born overseas was 16.8, compared with 27.1% nationally.

Although some people chose not to answer the census's question about religious affiliation, 48.7% had no religion, 41.8% were Christian and 1.1% had other religions.

Of those at least 15 years old, 243 (25.9%) people had a bachelor's or higher degree, and 150 (16.0%) people had no formal qualifications. The median income was $42,000, compared with $31,800 nationally. 249 people (26.5%) earned over $70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 492 (52.4%) people were employed full-time, 174 (18.5%) were part-time, and 12 (1.3%) were unemployed.^[5]

Opaki School is a co-educational state primary school for Year 1 to 8 students,^[6][7] with a roll of 154 as of February 2024.^[8] School buses serve the neighbouring settlements of Rangitumau, Mauriceville and Mikimiki.^[9]