In 1927, Lorna Violet Southwell and Osyth Potts, two Oxford University graduates founded St. George’s School. In their undergraduate days at St. Hugh's College, after the horrors of the First World War, they conceived the idea of founding a school in which children of all nationalities, religions and languages could share their learning and they hoped that with this experience behind them, the students would, as adults understand others better and thus contribute to the promotion of peace in the world.

The two founders were born in the very late Victorian period and grew up in the Edwardian era and were among the very first female students to be awarded degrees from Oxford University. Their experiences in this time of very rapid and social change influenced their ideas about the usefulness and purpose of starting an international school.

The school opened in 1927 in two chalets on the lakeside in Clarens with a student body of just 9. The land that the school now occupies was purchased in 1928 and the school building opened in January 1931. It has the distinction of being the first with a purpose-built school building in Switzerland.

During World War II, the school split with one half taking up residence in Shropshire, UK. Houses have always been an integral part of school. The first Houses were Diana and Minerva followed by Atalanta in 1938. More recently in the 21st century, Vesta was added. The House shield is keenly contested through a series of events: sports, maths, drama, music and art. Various additions and extensions have taken place including the modern languages wing in 1958, the library in 1977 and the Sports Hall in 1987.

Science labs and a new dining room have been built and a later addition including a new block of classrooms above. A major change took place in 1993 when boys were first enrolled, a total of 10 initially. Built to commemorate the 75th anniversary in 2002, the Henge is a popular area used as an outside classroom, a place to reflect and where students congregate. St. George’s became a member of the CIS (Council of International Schools) in 2005 and 2009 saw the first cohort of IB students (International Baccalaureate Diploma Programme).

In 2015 the school became a member of the Inspired Education Group, a leading global premium schools group, offering excellence to over 50,000 students in over 70 schools worldwide.

The crèche opened in 2016 enabling the school to provide the opportunity to educate children from the age of 18 months to 18 years. At the same time, Sport Etudes was introduced offering a bespoke programme for outstanding talent to those passionate and committed to their specific sport. The school will celebrate its centenary in 2027.