The Diocese of Argyll and the Isles (Latin: Diocesis Ergadiensis et Insularum) is a Latin Church ecclesiastical territory or diocese of the Catholic Church in Scotland, in the Province of Saint Andrews and Edinburgh.

The see is in the town of Oban where the seat is located at St Columba's Cathedral.

[1] The diocese was erected on 5 March 1878 following the restoration of the Scottish Catholic hierarchy.

On 28 December 2015 Pope Francis appointed Father Brian McGee to succeed the Right Reverend Joseph Toal as eleventh Bishop of Argyll and the Isles.

[1] After its establishment in 1878, the seat of the diocese was in various buildings each overlapping the same site:[2] The diocese is organised into three deaneries each with several parishes:[4] Dean: Fr Michael Hutson Dean: Fr Roddy McAuley Dean: Fr Michael MacDonald There are Catholic primary schools in Rothesay, Oban, Dunoon and Fort William.