Tranquillity International School And Kindergarten was founded in 2001 by a group of international parents in Tartu. The school started with seven children in grades 1 to 6 and was located in one classroom in the same building. As the number of students grew in the following years, the international preschool group was opened in the neighboring kindergarten.

In 2005, as the demand for international English language education kept increasing in Tartu, Tranquillity International School and Kindergarten moved to an elegant building at Vanemuise 28. The schoolhouse was fully renovated in 2016–2017 for the needs of the school's growing student body. The school's home was initially built in 1956 and functioned as a hotel until 2004. The building is located in an area of cultural and environmental value. The greenery of parks surrounds it.

Since 2017, the school has been authorized to teach the International Baccalaureate Primary Years Programme. The school is operated on a non-profit basis by a management board elected by the members of NGO Tranquillity International School.

As of the 2021/2022 school year, Tranquillity International School has 700 students in grades 1 to 9 and 350 children in kindergarten. The school's faculty consists of 110 part- and full-time teachers, student support specialists, and other staff members.