Founded in 1948 by Lady Peake, wife of the British Ambassador, the Foreign School initially operated with one staff member and parent volunteers teaching elementary students using British texts at the American Mission. By 1950, the school expanded to K-8 using American Forces’ teaching manuals and changed its name to the International School of Belgrade in 1952.

The campus relocated to its present Lower School location in 1957, expanding with new buildings over time. In 1962, the school began receiving U.S. Government financial grants, fostering relationships with U.S. universities and educational programs. Accreditation by NEASC and ECIS came in 1981, with subsequent IB program authorizations by 2010. ISB's growth continued with the opening of new campuses and technological advancements, including a landmark technology plan in 2009 and accreditation alignments. Celebrating its 75th year in 2023, ISB remains committed to excellence in education.