It was formed in 1973 when the existing Convent of the Sacred Heart Grammar and secondary schools in the city were re-organized on a comprehensive basis to provide secondary education for all the Catholic girls of the greater Armagh area.

Saint Catherine's College was a boarding school in the earlier 1900s and was formed by the Sacred Heart trust to provide education for young girls of all backgrounds.

Saint Catherine's College is situated on a 30-acre (120,000 m2) site off the Convent Road in Armagh and the existing school buildings have been refurbished and upgraded to ensure the provision of the most modern technological and sporting facilities.

In 2018, 73.3% of its entrants achieved five or more GCSEs at grades A* to C, including the core subjects English and Maths.

The school is involved in many sporting activities including Gaelic football and camogie.