The site is a National Monument in the care of the Gowran Development Association (GDA)[4] and the Office of Public Works (OPW).

The presence of an Ogham stone on the site, which is on display in the chancel, suggests there was a place of worship here dating back 2000 years to Celtic times or beyond.

In 1312 A.D. Edmund Butler, Earl of Carrick and Lord Deputy of Ireland made a binding agreement before the Kings Justice in Dublin with the Dean and Chapter of St Canice's Cathedral in Kilkenny to financially support four priests in St. Mary’s Church Gowran to celebrate masses forever, for himself, his wife Joan, his son, James Butler, 1st Earl of Ormonde, his daughters and his ancestors living and dead.

The oldest inscribed monument in the church is the Christianised Ogham Stone [2] from the 3rd or 4th century, which was found on the site during the rebuilding of the chancel in 1826.

Edmund Barry's reading as "DALO MAQA MUCOI MAQUI-ERACIAS MAQI LI", that is, "Dalach, grandson, of Mac-Eirche, who was son of Lia".

However it was their descendant Edmund Butler, Earl of Carrick, who established the Collegiate Church in Gowran, who first chose to be buried there.

The Gowran Ogham Stone; the Effigy of Ralph; the effigies of James Butler, first Earl of Ormonde, and his wife, lady Eleanor De Bohun; the Butler Knight Tombs; the Agar Monument; a stained glass window dedicated to Aubrey Cecil White; Toler Aylward windows; and many other artefacts are on display in the chancel.

On 23 August 2014, during Heritage Week, there was a commemoration of World War One, including a talk and presentation on Aubrey Cecil White.