The Roman Catholic Diocese of Diamantino (Latin: Dioecesis Adamanteae) is a diocese located in the city of Diamantino in the ecclesiastical province of Cuiabá in Brazil.

• 22 March 1929: Established as Territorial Prelature of Diamantino from the Metropolitan Archdiocese of Cuiabá
• 16 October 1979: Promoted as Diocese of Diamantino
• 6 February 1982: Lost territory to establish Diocese of Sinop
• 23 December 1997: Lost territory, along with Diocese of Ji-Paraná, to establish Diocese of Juína

• Bishops of Diamantino (Latin Rite)
  • Vital Chitolina, S.C.I. (2011.12.28 - present)
  • Canísio Klaus (1998.08.26 – 2011.12.28), appointed Bishop of Santa Cruz do Sul, Rio Grande do Sul
  • Agostinho Willy Kist, S.J. (1982.11.15 – 1998.08.26)
  • Henrique Froehlich, S.J. (1979.10.16 – 1982.03.25), appointed Bishop of Sinop, Mato Grosso
• Prelates of Diamantino (Roman Rite)
  • Henrique Froehlich, S.J. (1971.11.29 – 1979.10.16)
  • Alonso Silveira de Mello, S.J. (1955.06.13 – 1971.11.29; Apostolic Administrator 1949.11.12 – 1955.06.13)

• Canísio Klaus (1998)

• GCatholic.org
• Catholic Hierarchy

14°24′13″S 56°25′26″W / 14.4035°S 56.4238°W / -14.4035; -56.4238