Leo Club of St Johns College was the first Leo Club to be formed in the Northern Province of Sri Lanka. It was inaugurated on the 2^{nd of}   March 1981 under the patronage of the Lions Club of Jaffna, and the guidance of the late Principal Mr. C. E. Anantharajan.

The word “LEO” stands for LEADERSHIP, EXPERIENCE and OPPORTUNITY.

The Leo Club develops and fosters leadership skills and cohesive teamwork by encouraging members to lead and participate in activities which are focused on community service. Students participate in various projects in the areas of health, the elderly, children, and persons who are differently abled, literacy and education, and self-development. Enrolment to the Leo Club is open for students who are in the Lower and Upper Sixth classes (Advanced Level ).

A representative from the Lions Club of Jaffna attends the regular meetings along with the staff advisor of the College to direct, encourage and support the students with their various projects.