At the request of the Catholic community in Calcutta, Dr Bakhaus, a chaplain, visited Loreto Abbey, Ireland in 1840 and requested Mother Teresa Ball, to send some dedicated sisters to Calcutta, to set up a school for the Catholic children in the city. In response to the request, Mother Teresa Ball arranged to send a band of seven Loreto sisters and five Postulants, all in their twenties, under the leadership of Mother M. Delphine Hart. Before leaving Ireland, the young ladies were warned that they would probably never see their country again.

Sailing on a ship named The Scotia, a group sisters belonging to the institute of the Blessed Virgin Mary, left Dublin on 1st September 1841 and landed at Babughat, Calcutta on 29 December 1841. They were formally welcomed by Bishop Carew and after the customary religious ceremony at the Cathedral on Portuguese Church Street, they were housed in a beautiful and spacious three storeyed building, situated at 5 Middleton Row. Earlier, the building was occupied by different important persons of the city at different times, which included, among others, Henry Vansittart, Governor of Bengal, Sir Elijah Impey, the infamous First Chief Justice of the Supreme Court in Calcutta and the Second Anglican Bishop of Calcutta, Bishop Heber. Loreto House School was opened in that building on 10 January 1842 with 60 students. In other words, the students were taught in a building, where nuns resided under the leadership of Mother Delphine Hart, assisted by Sr. Teresa Mons and Sr. Martina McCann.

Located at 7 Middleton Row, Loreto House is the oldest and the first Loreto institution that was established in India. It was also one of the few all-girls Catholic schools during that time.

However, before the opening of the school, the construction of St. Thomas' Church had begun within the same campus from 11 November 1841. Apart from that, Archbishop of Calcutta also constructed his personal residence next to the church and at the doorstep of Loreto House, which in those days, was known as St. Thomas' House.

With the passing of time, the school needed more space to accommodate its growing number of students and by the turn of the century the old Loreto House building was extended as a part of the planned programme. After a few more years, St. Thomas’ House was also purchased from the Archbishop, to accommodate the Infant School classes. Later, on the 2nd day of February 1912, the newly established Loreto College was housed in that building. But, despite the earlier extension, the old Loreto House building was still not big enough to fulfill its purpose. To solve the space problem, plot no.8 Middleton Row was purchased and on the combined ground of no 7 and no 8, St Anne’s building was constructed. Finally, a three storey wing was constructed in 1950s, at right angles to Middleton Street.

Unfortunately, the old Loreto House building had to be demolished during 1958-1961, as it was declared unsafe by the city architects. Today, the remaining original buildings in the campus include only a part of the building where the college was first established and the St Thomas’ Church, which lost its steeple in 1897, due to a severe earthquake.

Though the school was initially established for the education of only the local Catholic girls, the restriction has been withdrawn long back. Today, there are two school buildings, one for the junior and middle school and the other for the senior school and its laboratories. The school follows the syllabus of the Council for the Indian School Certificate Examinations and accordingly prepares the students for ICSC and ISC examinations. To support the diverse talents of the students, the extracurricular activities of the School include a Dance Club, a Cookery Club, Mathematics and Science Clubs, along with games. In the heart of the city, the school is equipped with three basketball courts, along with a spacious lawn for children to play.