Founded on May 11, 1983, as MO/Sevanagala Kanitu Viduhala, the school began with 143 students, two teachers, and classes from Grade 1 to 7. The first principal, Mr. S. Sugath Jayasekara, led the institution with dedication.

In 1990, the school was renamed MO/Sevanagala Maha Vidyalaya, marking a new phase of growth. Later, in 2013, the Primary Section was separated to form a new school, allowing for a more focused secondary education system. Following this change, the school was renamed MO/Sevanagala Secondary School.

Today, Sevanagala Secondary School continues its mission of academic excellence, shaping the future of its students with dedication and pride.