It is located in the town centre, on the way from Kozhencherry to the district capital Pathanamthitta.

[1] In the early twentieth century, Kozhencherry was a small village in Pathanamthitta Taluk of Quilon District in the princely state of Travancore.

The naming system adopted in Kerala schools are as follows.

An English Medium School was opened in Kozhencherry by the Kottayam (Anglican) Mission in 1822 with 40 students and two teachers.

In 1918 approval was given to start High School Classes (Forms IV, V and VI).

From that year onwards it was known as St. Thomas Higher Secondary School.