The history of St.Brigid's dates back to 1939. At this time the Principal of St. Mary’s National School and the Community realized the need for Second Level Education for senior girls and so in September 1939 a “Secondary Top” was begun – a senior class attached to the Primary School, staffed at first by Primary School teachers and following the approved Secondary School syllabus. This ran successfully for ten years – one large room in the National School being allocated to it.

In 1949 these Secondary classes were amalgamated with St. Brigid’s Missionary School – classes, in order to give the aspirants there the opportunity to follow a Secondary School program and do State exams. Classes were transferred to the school quarters attached to the Missionary School. The School, with 60 pupils, now called St. Brigid’s Secondary School, was officially recognised by the Department of Education, Secondary Branch, in September 1949. The School offered a four-year cycle and a wide range of subjects was provided. In 1949 St. Brigid's Secondary School, with just 60 pupils, was officially recognised by the Department of Education. Extensions and renovations were carried out and its first lay teacher was employed in that year.

The school offered a 4 year cycle and a wide range of subjects were provided. A small fee of £10 a year was paid by pupils who could afford it, but no one was excluded if they could not pay.

By 1953, with 93 pupils on rolls, specialist rooms for Art, Sewing, Shorthand and Typewriting and a lunchroom were provided and St. Mary’s Convent National School Cookery Hall was shared by both schools. From the beginning this Secondary School provided an all round education for its pupils, equal emphasis being placed on academic and non-academic subjects. Over the next decade the numbers of pupils rose steadily and this required more facilities. Records show how music, drama, debates, physical education, sport, and other cultural activities were fostered and the school has the honour of being the acknowledged cradle for camogie in this county.

A site was chosen and in May 1959 the foundation stone for a new school was laid. As there were no grants available for Secondary School buildings at this time, the total cost (£40,000 approx) was provided by the sisters of Mercy. This School, comprising an assembly hall, three classrooms, a science laboratory and cloakrooms was opened in September 1960. From this small structure the nucleus of what we know today as St. Brigid’s College was formed.

As the numbers increased and more rooms were needed, the sisters decided they had no alternative but to build on a new site. This was chosen on the right hand side of the entrance gate. This new building comprising an assembly hall, cloak rooms three class rooms and a science laboratory was built by the sisters at a cost of approximately £40,000 and opened in September 1960.

From this small structure, the nucleus of what we know today as St. Brigid's College was formed. From 1960 onwards the history of St Brigid's College is one of slow but determined continual growth. As numbers grew the buildings grew and as the curriculum widened girls were prepared, not only for entrance to teacher training and the civil service, but for entrance to all professions in university and public life.

By 1969 the main building was again inadequate to meet the needs of a growing school. The sisters again built the major portion of the school and for this they received a Dept.of Education grant for the first time and the whole complex was named St Brigid's College.

In 1971 in order to provide specialist rooms and more amenities and by now catering for over 300 pupils the sisters took over the recently vacated old National school, renovated and modernised part of it at their own expense and attached it to the main building.

In 1980 with numbers climbing towards 400 the remainder of the old primary school was modernised and added to the main building costing the school £25,000+ with no state aid. New offices and ancillary accommodation were also provided.

In 1990 the McAuley Lecture/Demonstration Theatre was built and additional cloakroom facilities provided to accommodate the now 600-pupil school. The pupil enrolment which began with 60 pupils in 1949 had increased ten-fold by 1990.

In 1992, the new sports hall was built and blessed, again without any state aid, having been funded through cash donations and sponsorship. Due to the generosity of the Sisters of Mercy, Parents and friends of St. Brigid’s the new Sports Hall was opened in 1992.

In 1994 a second Art Room and cloakrooms were added while later in that decade the windows and central heating were replaced. In 2004/2005 two new classrooms, special needs rooms, a lift and an enlarged staffroom were built at the same time as the whole school was made wheelchair accessible.

In 1995 showers and changing rooms were added.

In 2005 came the addition of two new classrooms a special needs room, Chemistry Preparation room were added and a lift was installed.

From its humble beginnings the school has developed into what now must be one of the largest and best equipped rural secondary schools in the country.