It has campuses in Earl's Court, Chelmsford, Plymouth, and Nottingham, with growing links with other churches, colleges and dioceses throughout the United Kingdom and beyond.

The college was formed as a merger between the former North Thames Ministerial Training Course, which was based in the dioceses of London and Chelmsford, and St Paul’s Theological Centre (part of Holy Trinity, Brompton).

In 2013, St Mellitus North West was established at Liverpool Cathedral, reestablishing full-time Anglican ordination training in that area for the first time in more than 40 years.

This venture was directed by Jill Duff (now Bishop of Lancaster), in partnership with five dioceses in that area (Blackburn, Carlisle, Chester, Liverpool and Manchester).

[9] The college is named after St Mellitus, one of the least known but most significant figures in the establishment of the church in London and Essex – a key moment in the conversion of the British Isles.