For a year after this he resided with Ambrose Lisle Phillips at Grace Dieu Manor, and then he went with John Henry Newman to Rome, where he was ordained priest in 1847.

Coffin joined the Oratory of St. Philip Neri, and in 1848-9 he was provost of the Oratorian community at St. Wilfrid's, Cotton Hall, Staffordshire.

In 1855 he was chosen Rector of St. Mary's Church in Clapham, and in 1865 appointed to the office of Provincial Superior, in which he was successively confirmed every three years until his elevation to the episcopate.

He was consecrated by Cardinal Howard in the church of St. Alfonso, on the Esquiline, at Rome, 11 June 1882, and enthroned at St George's Cathedral, Southwark, on the 27th of the following month.

Coffin published English translations of many of the works of Alphonso de' Liguori; and of Blosius's Oratory of the Faithful Soul.