Hertsmere is a local government district with borough status in Hertfordshire, England. Its council is based in Borehamwood. Other settlements in the borough include Bushey, Elstree, Radlett and Potters Bar. The borough contains several film studios, including Elstree Studios and the BBC Elstree Centre at Borehamwood. The borough borders Three Rivers, Watford, St Albans, and Welwyn Hatfield in Hertfordshire and the three north London boroughs of Harrow, Barnet and Enfield. Hertsmere is located mainly within the M25 Motorway.

Hertsmere was created on 1 April 1974 under the Local Government Act 1972, covering the whole area of three former districts and a single parish from a fourth district, which were all abolished at the same time:^[2]

• Aldenham parish from Watford Rural District
• Bushey Urban District
• Elstree Rural District
• Potters Bar Urban District

The Potters Bar Urban District (which coincided with the parish of South Mimms) was historically part of Middlesex, but had been transferred to Hertfordshire on 1 April 1965 when Greater London was created and Middlesex County Council abolished.^[3]

The name "Hertsmere" was coined for the new district by combining the common abbreviation of Hertfordshire ("Herts") with "mere", an archaic word for a boundary, referencing the area's location on Hertfordshire's border with Greater London and also the fact that it straddles the historic county boundary between Middlesex and Hertfordshire. The name is reflected in the council's coat of arms, which shows a hart upon the battlements of a boundary wall.^[4]

The district was awarded borough status on 15 April 1977, allowing the chair of the council to take the title of mayor.^[5]

The borough was originally in the Metropolitan Police District, despite being outside the modern Greater London boundaries. It was transferred to Hertfordshire Constabulary in 2000.

Hertsmere is the location of Elstree Film and TV Studios, which produces such shows as Strictly Come Dancing, Who Wants To Be A Millionaire, Dancing on Ice, and was the location for the Big Brother house. The studios were bought by Hertsmere Borough Council in 1996 and are now operated via Elstree Film Studios Limited, a council-controlled company.^[6]

Hertsmere is also the location for BBC Elstree Centre, the site of EastEnders, Holby City, and formerly the home to Top of the Pops, before its move to BBC TV Centre.

The area was also home to other TV and film studios, including MGM, until this was demolished for residential development, and is now an area called Studio Way.

Hertfordshire has a two-tier structure of local government, with the ten district councils (including Hertsmere Borough Council) providing district-level services, and Hertfordshire County Council providing county-level services. In some areas there is an additional third tier of civil parishes.^[9]

Since the last boundary changes in 2019, the council comprises 39 councillors elected from 16 wards, each of which returns either two or three councillors. Elections for the whole council are held every four years.^[17]

In 2003, the Borough Council started to present a small number of Civic Awards to people who live or work in Hertsmere 'in recognition of work undertaken for the benefit of residents of the Borough'.

The borough contains five parishes:

• Aldenham (includes Radlett)
• Elstree and Borehamwood (Town)
• Hertsmere Meriden
• Shenley
• South Mimms and Ridge

Four of the parishes have parish councils, with Hertsmere Meriden instead having only a parish meeting. Bushey and Potters Bar are unparished areas, being directly administered by Hertsmere Borough Council.

The 2011 census showed that Hertsmere was the second most Jewish local authority area in the United Kingdom, with Jews comprising one in seven residents (the area with the highest Jewish population being the London Borough of Barnet).^[18] In the 2021 census Hertsmere overtook Barnet to become the most Jewish local authority area, with Jews comprising one in every six residents. Jews form a plurality of the population in two wards of the borough, Bushey Heath and Elstree.