Cathedral of Christ the King, Mullingar, Catholic cathedral in Mullingar, Ireland.

The Cathedral of Christ the King is a Renaissance-style basilican church near Mullingar's centre, beside the Royal Canal. Dublin firm William Byrne & Sons designed it with twin towers about 55 metres high, topped by bronze crosses. It was built of granite from Barnacullia quarries in County Dublin and seats 5,000 people.

Planning for a replacement of the Cathedral of the Immaculate Conception (1836–1936) began in 1920. Building started in March 1933; Bishop Thomas Mulvany laid the foundation stone on 6 August 1933, and the cathedral opened on 6 September 1936. At the request of Pope Pius XI it became the first cathedral dedicated to Christ the King, and it was consecrated in 1939.

The cathedral's best-known artworks are the mosaics by Russian-born artist Boris Anrep in the chapels of Saint Anne and Saint Patrick. The Patrick mosaic shows him lighting the Paschal fire on the hill of Slane, the firewood laid out as a Christogram. In the Anne mosaic the name is spelled "Anna", and the saint's face is said to resemble the poet Anna Akhmatova, with whom Anrep had an affair during World War I.

The cathedral stands near Mullingar town centre, beside the Royal Canal, and seats 5,000 people. Visitors enter through the main doors beneath the twin towers; the Anrep mosaics are in the chapels of Saint Anne and Saint Patrick inside. Check Mass times before travelling, as the building is an active parish church.

This church was among the first deliberately dedicated to a modern religious concept of the 20th century. The emphasis on Christ as King reflected a theological focus that was relatively new at that time.