The school is named in honour of St. Catherine of Siena (the founder of the Dominican Congregation) whose family name was Benincasa. Benincasa was founded by the Dominican Sisters at Sion Hill in the late 1950s, and included in the Department of Education and Science system in 1962. In 1962 the Department of Education took over funding of the school.

Benincasa was established in the 1950’s as a class for children with special needs who were siblings of children enrolled in Sion Hill Primary School, which was also run by the Dominican Order. The founder and first teacher was Nancy Jordan, a Montessori Director. Nancy Jordan became the school’s first Principal.

It was first housed in a small cottage on the grounds of Sion Hill, however that cottage is no longer standing. Benincasas’ current property in Blackrock, Co. Dublin was bought in 1967. The large house was built in the 1800’s and first appeared on a street map in 1839. The property was owned at different stages by well-known people including the Earl of Pembroke and the Goodbody family.

In 2000 the school had this stained glass window fitted. Designed by artist Des Devitt and called ‘Tree of Life’. It is located over the main staircase where students and staff see it everyday.