The Iona Cathedral Trust was established by a Deed of Trust in 1899 by the eighth Duke of Argyll who made over the Cathedral and all ecclesiastical grounds and buildings on Iona to the trustees in perpetuity, as varied by an Arrangement approved by Interlocutor of the Court of Session dated 12 November 2004 and further varied by a Reorganisation Scheme as approved by the Office of the Scottish Charity Regulator under the Charities and Trustee Investment (Scotland) Act 2005 on 30 June 2010.
A majority of the trustees hold office by virtue of the office they hold within The Church of Scotland or they are nominated as a trustee by the Principal Clerk of the General Assembly of The Church of Scotland. One of the trustees is the Scottish Episcopal Bishop of Argyll and the Isles or is a person nominated by him. Another trustee is the Roman Catholic Bishop of Argyll and the Isles or a person nominated by him. Finally, one trustee is nominated by Iona Community Council.