In 1154 the Norwegian church created a diocese for its overseas holdings in the Irish Sea - the Hebrides, the islands along the west coast of Scotland, and the Isle of Man. The Norse name was Suðreyjar, meaning the southern isles, in contrast to the Norðreyjar, the northern isles of Orkney and Shetland. This Sudrey diocese was a suffragan of the great Norwegian archdiocese of Nidaros at Trondheim. Norway controlled these scattered islands until 1266, when the western isles were ceded to Scotland. The Isle of Man was separated from the rest in 1334, coming under the suzerainty of the English Crown. The diocese remained, in a much-reduced form. Today the bishop's office is in Douglas, and the cathedral - St German's - is in Peel. It is one of two Church of England dioceses outside the United Kingdom; the other is the Diocese in Europe.

The name itself has been argued over for centuries. The Isle of Man was originally one of the southern isles in the old Norse sense - it was a Suðrey. The addition of "and Man" probably crept in during the seventeenth century, when scholars had forgotten the Norse origin and assumed Sodor must refer to somewhere other than Man itself. One suggestion is that St Patrick's Isle at Peel, where the original cathedral stood, became known as Sodor by association. By the late 1500s, official documents used Sodor, Man, or both, sometimes adding all three for safety. The 1610 grant of lordship of the island to the Earl of Derby covered "the Patronage of the Bishopricke of the said Isle of Mann, and the Patronage of the Bishopricke of Sodor, and the Patronage of the Bishopricke of Sodor and Mann." Until 1604 bishops signed themselves Sodorensis. Between 1684 and 2007 they signed Sodor and Man. The present bishop, like her predecessor, signs Sodor as Mannin - the Manx Gaelic equivalent.

The original cathedral, on St Patrick's Isle at Peel, fell into disuse during the eighteenth century. The site was a small island connected to the mainland by a causeway, exposed to the weather, and steadily ruinous. For most of the nineteenth and twentieth centuries the diocese had no functioning cathedral at all. The bishop's chapel at Bishopscourt, near Kirk Michael - a Gothic Revival building rebuilt in 1814 and again in 1858, dedicated to St Nicholas - served as a pro-cathedral. Bishopscourt was sold in 1979, and the following year the parish church of St German in Peel was elevated to cathedral status by an Act of Tynwald, the Manx parliament. Twice before, in 1836 and 1875, English plans had tried to absorb the diocese - first into Carlisle, then into the new diocese of Liverpool. Both proposals were defeated. The Manx kept their bishop.

Because the Isle of Man is not part of the United Kingdom, the Bishop of Sodor and Man cannot sit in the House of Lords as a Lord Spiritual, unlike the senior diocesan bishops of England. Instead, the bishop is an ex officio member of the Legislative Council of the Isle of Man, the upper house of Tynwald. The appointment is still made on the advice of the British Prime Minister, but uniquely - unlike English diocesan bishops, who are formally elected by their cathedral canons under royal licence - the Bishop of Sodor and Man is appointed directly by the monarch, by letters patent. Thomas Wilson, bishop from 1697 to 1755, used the island's strange jurisdictional status to introduce worship in the Manx Gaelic language, which the Act of Uniformity 1662 had not been able to suppress on an island where it did not legally apply. The diocese administers 40 churches in 15 parishes today, grouped into four Mission Partnerships that replaced the older rural deanery structure in 2013.