Model United Nations (MUN) is an educational simulation in which students learn about diplomacy, international relations and the United Nations. Students participating in a MUN conference as delegates or chairs will acquire significant skills, as MUN involves and teaches public speaking, debating, research and writing skills, in addition to critical thinking, teamwork and leadership abilities.

The BISJ MUN society, for students in Y7-IB2, meets after-school once per week to complete skills training and conference preparation. Students are then selected to attend conferences within Saudi Arabia, the Middle East and Europe where they discuss and debate challenges facing the world today from water rights to nuclear weapons. In the last year, students have attended conferences in Jeddah, Berlin and the Hague.

Student performance is recognised by conferences with formal certificates, as well as awards for outstanding individual performances.