The Roman Catholic Diocese of Nkayi (Latin: Nkayien(sis)) is a diocese located in the city of Nkayi in the ecclesiastical province of Pointe-Noire in the Republic of the Congo.

• 5 December 1983: Established as Diocese of Nkayi from the Diocese of Pointe-Noire

• Bishops of Nkayi (Roman rite), in reverse chronological order
  • Bishop Daniel Mizonzo (since 16 October 2001)
  • Coadjutor Bishop François Halyday Mbouangui (since 1 December 2025)
  • Bishop Bernard Nsayi (7 July 1990 – 16 October 2001)
  • Bishop Ernest Kombo, S.J. (5 December 1983 – 7 July 1990), appointed Bishop of Owando

• Roman Catholicism in the Republic of the Congo

• GCatholic.org
• Catholic Hierarchy

4°10′54″S 13°17′30″E / 4.1817°S 13.2918°E / -4.1817; 13.2918