Christ College is built on the site of the thirteenth century Dominican Friary of St Nicholas (established in about 1250). The friary buildings that remain, the chapel and the dining hall, have been used daily by current pupils since their rebuilding in 1864.

In 1538 the Friary land and buildings were surrendered to King Henry VIII during the Dissolution. Bishop Barlow, Bishop of St David's, later persuaded Henry VIII to transfer the college at Abergwilli to Brecon to establish a school on the site of the former friary.

On January 19th 1541 Henry VIII founded the College of Christ of Brecknock by Royal Charter. Its intention was to train older boys for ordination into the Church and teach younger boys the rudiments of learning under the direction of a Lecturer in Divinity.

The Chapel was almost completely destroyed in the hands of Roger Thomas at the end of the English Civil War. It was restored in 1660 through the generous benefactions of Bishop Lucy, one of three Bishops of St Davids who are buried in the chapel.  

The College of Christ of Brecknock alternately flourished and floundered in the centuries that followed. After a period of dilapidation, 'Christ's College' was re-founded by Act of Parliament in 1853 and re-opened on January 31st 1856 under the headmastership of the Rev. J D Williams. 

School House opened in 1864, providing classrooms and dormitories for 40 boarders. As the school further expanded under the headmastership of the Rev. Daniel Lewis Lloyd, more classrooms, a science laboratory and a big school room were opened in 1881.

The design of the East window in the newly restored chapel (1864) was based on the original seal of the College of Christ of Brecknock. The design of the stained glass of the dining hall (1864) includes the 'h' from which the school emblem is derived. 

57 names are inscribed on the original First World War memorial tablet in the antechapel which, together with the memorial cross, was designed (1922) by W M Best whose three brothers were killed in action. They are also commemorated by the Memorial Pavilion (1924).

The Hostel (1891) was renamed Donaldson's House in 1955 to honour Canon A E Donaldson, a retiring member of staff. With Orchard House (1921) and School House (1864), it was one of three boys boarding houses in 1955. It became a girls house in 1998.

The original Memorial Hall (1955) was built as a memorial to those who lost their lives in the Second World War. The remodeled Y Neuadd Goffa (2013) retains the original auditorium at its heart, with a new gallery and studio space within the extended modern glass structure. 

Alway House was opened in 1962 as a dedicated House for junior boys - Forms One and Two (Years 7 and 8). Younger pupils had previously resided in the senior houses, either in the Housemaster's private accommodation or in 'small' dorms.

School House was split into School House Red and School House Blue in 1957 to accommodate the increasing number of boarders. It was reunited again in 1994 as School House when School House Blue moved up the hill to become St David's House.

Sally Stewart, the first girl to be enrolled in Christ College joined the school in September 1985. De Winton, originally a house for Sixth Form girls, was was opened in 1987. When girls were admitted throughout the school in 1995, Christ College became fully co-educational.

Saint Nicholas House, the junior section of Christ College was opened in 2014. The Feast of St Nicholas, a day on which boys historically enjoyed ale and cakes, was celebrated (without the ale) on 6th December 2014 by pupils in Years 3-6.

Celebrating 475 years since its original foundation, in 2016 Christ College signed an agreement for King Henry VIII College, a sister school in Malaysia. 'KH8' opened on 3 September 2018 with nine Old Breconians amongst the teaching staff.