Date | Country | Change |
| 2004 |  Jordan | Territory Dependent on the Patriarch of Jordan (Chaldean Rite) was established |
| 2004.01.03 |  Mexico | Diocese of Irapuato was established (from Metropolitan Archdiocese of Morelia and Diocese of León and became suffragan of San Luis Potosí) |
| 2004.02.24 |  Poland | Diocese of Bydgoszcz was established (from Metropolitan Archdiocese of Gniezno, Diocese of Koszalin–Kołobrzeg and Diocese of Pelplin and became suffragan of Gniezno) |
| 2004.02.24 | Poland | Archdiocese of Łódź was promoted as Metropolitan Archdiocese of Łódź (with suffragan see Łowicz) |
| 2004.02.24 | Poland | Diocese of Świdnica was established (from Metropolitan Archdiocese of Wrocław and Diocese of Legnica and became suffragan of Wrocław) |
| 2004.02.27 |  India | Diocese of Raipur was promoted as Metropolitan Archdiocese of Raipur (with suffragan sees Ambikapur, Jagdalpur and Raigarh) |
| 2004.05 |  Italy | Titular Episcopal See of Arna was restored |
| 2004.06 | Italy | Titular Episcopal See of Biccari was restored |
| 2004.06 | Italy | Titular Episcopal See of Carmeiano was restored |
| 2004.06 | Italy | Titular Episcopal See of Egnazia Appula was restored |
| 2004.06 | Italy | Titular Episcopal See of Erdonia was restored |
| 2004.06.03 | India | Diocese of Trivandrum was promoted as Metropolitan Archdiocese of Trivandrum (with suffragan sees Alleppey, Neyyattinkara, Punalur and Quilon) |
| 2004.06.15 |  Spain | Archdiocese of Barcelona was promoted as Metropolitan Archdiocese of Barcelona (with suffragan sees Sant Feliu de Llobregat and Terrassa and lost territory to establish Diocese of Sant Feliu de Llobregat and Diocese of Terrassa) |
| 2004.06.15 | Spain | Diocese of Sant Feliu de Llobregat was established (from Archdiocese of Barcelona and became suffragan of Barcelona) |
| 2004.06.15 | Spain | Diocese of Terrassa was established (from Archdiocese of Barcelona and became suffragan of Barcelona) |
| 2004.06.24 |  Philippines | Apostolic Vicariate of Baguio was promoted as Diocese of Baguio (became suffragan of Nueva Segovia) |
| 2004.06.24 |  South Korea | Diocese of Uijeongbu 의정부 was established (from Metropolitan Archdiocese of Seoul 서울 and became suffragan of Seoul 서울) |
| 2004.07 |  Iraq | Titular Episcopal See of Hirta was established |
| 2004.07.03 |  Colombia | Diocese of Villavicencio was promoted as Metropolitan Archdiocese of Villavicencio (with suffragan sees Granada and San José del Guaviare) |
| 2004.10 | Italy | Titular Episcopal See of Galtellì was restored |
| 2004.10 | Italy | Titular Episcopal See of Ostra was restored |
| 2004.10 | Italy | Titular Episcopal See of Ottana was restored |
| 2004.10.20 |  Brunei | Apostolic Prefecture of Brunei was promoted as Apostolic Vicariate of Brunei |
| 2004.11.20 |  Burkina Faso | Diocese of Dori was established (from Diocese of Fada N’Gourma and Diocese of Ouahigouya and became suffragan of Koupéla) |
| 2004.12.06 |  Ukraine | Archiepiscopal Exarchate of Kyiv–Vyshhorod (Ukrainian Rite) was promoted as Metropolitan Archdiocese of Kyiv (with suffragan sees Bučač, Kolomyia–Chernivtsi, Sambir–Drohobych, Sokal and Stryj and exchanged territory with Major Archdiocese of Lviv–Halyč–Kamyanets) |
| 2004.12.06 | Ukraine | Major Archdiocese of Kyiv–Halyč–Kamyanets (Ukrainian Rite) was established (from Major Archdiocese of Lviv–Halyč–Kamyanets) |
| 2004.12.06 | Ukraine | Major Archdiocese of Lviv–Halyč–Kamyanets (Ukrainian Rite) was demoted as Archdiocese of Lviv (lost territory to establish Major Archdiocese of Kyiv–Halyč–Kamyanets and exchanged territory with Archiepiscopal Exarchate of Kyiv–Vyshhorod) |
| 2004.12.18 |  Central African Republic | Diocese of Alindao was established (from Diocese of Bangassou and became suffragan of Bangui) |
| 2004.12.29 |  Brazil | Diocese of Castanhal was established (from Metropolitan Archdiocese of Belém do Pará and Diocese of Bragança do Pará and became suffragan of Belém do Pará) |
| 2004.12.29 |  USA | Diocese of Galveston–Houston was promoted as Metropolitan Archdiocese of Galveston–Houston (with suffragan sees Austin, Beaumont, Brownsville, Corpus Christi, Tyler and Victoria) |
