Mayfield is a suburb to the north of Blenheim's central district, in the Marlborough region of the South Island of New Zealand. Pollard Park and Lansdowne Park are large parks to the west and north of the suburb, and a racecourse lies to the northwest.

Mayfield covers 1.46 km (0.56 sq mi). It had an estimated population of 1,870 as of June 2024, with a population density of 1,281 people per km.

Historical population

Year	Pop.	±% p.a.
2006	1,470	—
2013	1,539	+0.66%
2018	1,674	+1.70%
Source:

Mayfield had a population of 1,674 at the 2018 New Zealand census, an increase of 135 people (8.8%) since the 2013 census, and an increase of 204 people (13.9%) since the 2006 census. There were 660 households, comprising 852 males and 822 females, giving a sex ratio of 1.04 males per female. The median age was 38.2 years (compared with 37.4 years nationally), with 324 people (19.4%) aged under 15 years, 303 (18.1%) aged 15 to 29, 768 (45.9%) aged 30 to 64, and 279 (16.7%) aged 65 or older.

Ethnicities were 77.1% European/Pākehā, 20.3% Māori, 3.9% Pasifika, 10.4% Asian, and 2.5% other ethnicities. People may identify with more than one ethnicity.

The percentage of people born overseas was 19.4, compared with 27.1% nationally.

Although some people chose not to answer the census's question about religious affiliation, 52.0% had no religion, 31.4% were Christian, 1.3% had Māori religious beliefs, 2.2% were Hindu, 0.2% were Muslim, 0.9% were Buddhist and 3.0% had other religions.

Of those at least 15 years old, 144 (10.7%) people had a bachelor's or higher degree, and 348 (25.8%) people had no formal qualifications. The median income was $29,400, compared with $31,800 nationally. 111 people (8.2%) earned over $70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 696 (51.6%) people were employed full-time, 222 (16.4%) were part-time, and 54 (4.0%) were unemployed.

Mayfield School is a coeducational contributing primary (years 1–6) school with a roll of 107 students as of November 2024.