The Japanese School in London (ロンドン日本人学校 Rondon Nihonjin Gakkō) is a Japanese international school in Acton, London Borough of Ealing. The school is incorporated as The Japanese School Limited (日本人学校有限会社 Nihonjin Gakkō Yūgen Kaisha). The Japanese Saturday School in London (, a Rondon Hoshū Jugyō Kō)Japanese supplementary school, is a part of the institution.
Junko Sakai (酒井 順子 Sakai Junko), author of Japanese Bankers in the City of London: Language, Culture and Identity in the Japanese Diaspora, described the school as one of the "geographical centres" of London's Japanese community.
In 1999 the Saturday school programme had three divisions: elementary school for ages 6–12, junior high school for ages 13–15, and senior high school, equivalent to the English sixth-form. The Saturday school uses three campuses: the Acton Campus (アクトン校舎 Akuton Kōsha), which uses the Japanese School in London building; the Brent Campus (ブレント校舎 Burento Kōsha), which uses the Whitefield School; and the Croydon Campus (クロイドン校舎 Kuroidon Kōsha), which uses the Croydon School for Girls.
The school, operated by the Japanese Ministry of Education, was established with the financial involvement of Japanese companies. It first opened as a supplementary school, with four teachers and 20 students, in the Convent of Our Lady Sion in September 1965. It was upgraded to an official supplementary school in 1974 when the Japanese Ministry of Education sent its first teacher; it had done so due to an increase in the student body. The day school was established on 18 June 1976. The Japanese Ministry of Education had sent Katsuya Tanaka, the first headmaster, to London the previous April.