Saint Agnes School opened its doors on September 8, 1930, on the Feast of the Nativity of the Blessed Virgin Mary. The Sisters of Notre Dame staffed the school, which began with 26 pupils. The first students of Saint Agnes School attended classes in houses on the property and at Saint Joseph Heights. The school grew rapidly, and in 1941 a framed building behind the new Church and facing Old State Road was built. It consisted of four classrooms and a large basement recreation area. This building was dedicated on August 24, 1941 and was meant to be an interim school building until a larger, more permanent building was needed.
Within a few years the school enrollment was increasing rapidly, and the larger school that had been foreseen was needed. Ground was broken in 1955 for a new school building which was completed and dedicated on February 10, 1957. The Sisters of Notre Dame continued to operate the school. This sisters lived at Saint Joseph Heights until 1960 when Saint Agnes built a convent near the north end of the school for the convenience of the sisters teaching at the school.
In the early 1960's, six classrooms and storage space was added to the north end of the school to accommodate the ever-increasing enrollment of the school, which had reached 879 children. This addition was completed in 1964. By 1967, Saint Agnes School enrollment peaked with 939 students. At that time the school was staffed by seventeen nuns and eleven lay teachers. All available space was used as classrooms, including rooms in the Church and Church basement and even at Covington Catholic High School, located down the street.
Ground was broken for new additions to the school on January 13, 1989. In 1990, the new addition to the school was opened. The addition included a multipurpose center, regulation-size gymnasium, science lab, computer lab, classrooms, enlarged kindergarten, guidance counselor's office, and new offices and faculty workroom.
In 2013, Saint Agnes moved forward with renovations to update the school's infrastructure, including new central heating, ventilation and air conditioning system, a new electric system, a state of the art computer network, computer labs and wireless capabilities. The renovation work also included improved lighting, new carpeting, ceiling and paint throughout the building, new doors, a walk-in refrigerator/freezer and various other improvements. All renovations were completed prior to the 2013-2014 school year.
In 1995, the Sisters of Notre Dame ended their administration of Saint Agnes School. However, the sisters and the parish have maintained a close relationship with sisters helping out in the school and parish in various capacities. The sisters administered and taught in the school for 65 years and this great favor to the parish has not been forgotten. In the time period between 1930 and 2014, 138 Sisters of Notre Dame have served at Saint Agnes.