St Muredach's Cathedral is the cathedral church of the Roman Catholic Diocese of Killala in Ireland.

It is located on the east bank of the River Moy in Ballina, County Mayo.

[2] The cathedral's construction was initiated by Bishop John MacHale (1791–1881) who served as the Bishop of Killala from 1825 to 1834 and the completion of the cathedral in 1834 coincided with his translation to the Archdiocese of Tuam.

The spire was completed in 1855 to the designs of the celebrated architect James Joseph McCarthy and further embellishment continued throughout the nineteenth century.

[3] The cathedral is situated in the townland of Abbeyhalfquarter.