ISOI encourages its students to become involved in athletics and provides a wide variety of choices in team and individual sports, varsity, middle school, and intramural athletics, as well as regular physical education classes.
ISOI is a member of the South Asia Inter-School Association (SAISA) and competes with other international schools in Pakistan, Bangladesh, India, Jordan, Nepal, Oman, and Sri Lanka. Tournaments are held in soccer, volleyball, basketball, track and field, cricket, tennis, and swimming.
Students in Middle School participate in SAISA West tournaments, with other international schools in Pakistan. Tournaments are held in basketball, volleyball, badminton, swimming, soccer, and track and field.