| Date | Country | Change |
| 1979 | Diocese of Oudtshoorn lost territory to Diocese of Keimoes | |
| 1979 | Titular Episcopal See of Dara Syrorum (Syriac Rite) was restored | |
| 1979.01.08 | Diocese of Holguín was established (from Metropolitan Archdiocese of Santiago and became suffragan of Santiago) | |
| 1979.01.08 | Diocese of Tuxtepec was established (from Territorial Prelature of Huautla and became suffragan of Antequera) | |
| 1979.01.15 | Metropolitan Archdiocese of Milano (Ambrosian Rite) lost territory to Diocese of Pavia | |
| 1979.01.21 | Diocese of Lodi exchanged territory with Diocese of Pavia | |
| 1979.01.21 | Diocese of Pavia exchanged territory with Diocese of Lodi | |
| 1979.02.05 | Diocese of Cuautitlán was established (from Diocese of Texcoco and Diocese of Tlalnepantla and became suffragan of México) | |
| 1979.02.05 | Diocese of Nezahualcóyotl was established (from Diocese of Texcoco and became suffragan of México) | |
| 1979.03.03 | Titular Metropolitan See of Serdica was suppressed (to Diocese of Sofia–Plovdiv) | |
| 1979.03.03 | Apostolic Vicariate of Sofia–Plovdiv was promoted as Diocese of Sofia–Plovdiv (gained territory from the suppressed Titular Metropolitan See of Serdica and without ecclesiastical province) | |
| 1979.03.15 | Apostolic Prefecture of Awasa was promoted as Apostolic Vicariate of Awasa | |
| 1979.03.28 | Apostolic Vicariate of Northern Norway was promoted as Territorial Prelature of Tromsø (without ecclesiastical province) | |
| 1979.03.28 | Apostolic Vicariate of Central Norway was promoted as Territorial Prelature of Trondheim (without ecclesiastical province) | |
| 1979.04.04 | Diocese of Cariati lost territory to Diocese of Crotone | |
| 1979.04.04 | Diocese of Cassano all’Jonio lost territory to Diocese of San Marco Argentano–Scalea | |
| 1979.04.04 | Diocese of Crotone lost territory to Archdiocese of Santa Severina | |
| 1979.04.04 | Diocese of San Marco was renamed as Diocese of San Marco Argentano–Scalea (gained territory from Diocese of Cassano all’Jonio and lost territory to Archdiocese of Cosenza) | |
| 1979.04.18 | Territorial Prelature of Rubiataba was renamed as Territorial Prelature of Rubiataba–Mozarlândia | |
| 1979.04.28 | Diocese of Irecê was established (from Diocese of Barra and Diocese of Ruy Barbosa and became suffragan of São Salvador da Bahia) | |
| 1979.04.30 | Metropolitan Archdiocese of Capua was demoted as Archdiocese of Capua (became suffragan of Napoli) | |
| 1979.04.30 | Metropolitan Archdiocese of Conza was demoted as Archdiocese of Conza (became suffragan of Benevento) | |
| 1979.04.30 | Diocese of Foggia was promoted as Metropolitan Archdiocese of Foggia (with suffragan sees Manfredonia, Ascoli Satriano, Cerignola, Lucera, San Severo, Troia and Vieste) | |
| 1979.04.30 | Metropolitan Archdiocese of Manfredonia was demoted as Archdiocese of Manfredonia (became suffragan of Foggia) | |
| 1979.04.30 | Metropolitan Archdiocese of Sorrento was demoted as Archdiocese of Sorrento (became suffragan of Napoli) | |
| 1979.05.03 | Apostolic Vicariate of Caroline and Marshall Islands was promoted as Diocese of Carolines–Marshalls (became suffragan of Suva) | |
| 1979.05.16 | Diocese of Silva Porto was renamed as Diocese of Kwito-Bié | |
| 1979.05.16 | Diocese of Luso was renamed as Diocese of Luena | |
| 1979.05.16 | Diocese of Serpa Pinto was renamed as Diocese of Menongue | |
| 1979.05.16 | Diocese of Pereira de Eça was renamed as Diocese of Ondjiva | |
| 1979.05.16 | Diocese of Henrique de Carvalho was renamed as Diocese of Saurimo | |
| 1979.05.16 | Diocese of Carmona e São Salvador was renamed as Diocese of Uíje | |
| 1979.05.21 | Diocese of Barreiras was established (from Diocese of Barra and became suffragan of São Salvador da Bahia) | |
| 1979.06.01 | Diocese of Itabira was renamed as Diocese of Itabira–Fabriciano | |
| 1979.06.01 | Diocese of Rawalpindi was renamed as Diocese of Islamabad–Rawalpindi | |
| 1979.06.10 | Diocese of Mileto lost territory to Metropolitan Archdiocese of Reggio Calabria and Diocese of Oppido Mamertina–Palmi | |
| 1979.06.10 | Diocese of Oppido Mamertina was renamed as Diocese of Oppido Mamertina–Palmi (gained territory from Diocese of Mileto) | |
| 1979.07.03 | Diocese of Santo Tomé was established (from Metropolitan Archdiocese of Corrientes and Diocese of Goya and became suffragan of Corrientes) | |
| 1979.07.04 | Diocese of Rourkela was established (from Diocese of Sambalpur and became suffragan of Cuttack–Bhubaneswar) | |
| 1979.08.20 | Diocese of Ciudad Guayana was established (from Metropolitan Archdiocese of Ciudad Bolívar and became suffragan of Ciudad Bolívar) | |
| 1979.08.29 | Territorial Prelature of Choluteca was promoted as Diocese of Choluteca | |
| 1979.10.15 | Diocese of Avellino exchanged territory with Territorial Abbacy of Montevergine | |
| 1979.10.15 | Diocese of Cava de’ Tirreni lost territory to Territorial Abbacy of Santissima Trinità di Cava de’ Tirreni | |
| 1979.10.15 | Territorial Abbacy of Montevergine exchanged territory with Diocese of Avellino | |
| 1979.10.15 | Diocese of Nocera de’ Pagani exchanged territory with Territorial Abbacy of Santissima Trinità di Cava de’ Tirreni | |
| 1979.10.15 | Metropolitan Archdiocese of Salerno lost territory to Diocese of Nocera de’ Pagani | |
| 1979.10.15 | Territorial Abbacy of Santissima Trinità di Cava de’ Tirreni lost territory to Diocese of Diano–Teggiano and Diocese of Vallo di Lucania | |
| 1979.10.16 | Territorial Prelature of Carolina was promoted as Diocese of Carolina | |
| 1979.10.16 | Diocese of Cascavel was promoted as Metropolitan Archdiocese of Cascavel (with suffragan sees Foz do Iguaçu, Palmas and Toledo) | |
| 1979.10.16 | Territorial Prelature of Diamantino was promoted as Diocese of Diamantino | |
| 1979.10.16 | Territorial Prelature of Formosa was promoted as Diocese of Formosa | |
| 1979.10.16 | Territorial Prelature of Guajará-Mirim was promoted as Diocese of Guajará-Mirim | |
| 1979.10.16 | Territorial Prelature of Guamá was promoted as Diocese of Guamá | |
| 1979.10.16 | Territorial Prelature of Humaitá was promoted as Diocese of Humaitá | |
| 1979.10.16 | Territorial Prelature of Marabá was promoted as Diocese of Marabá | |
| 1979.10.16 | Diocese of Maringá was promoted as Metropolitan Archdiocese of Maringá (with suffragan sees Campo Mourão, Paranavaí and Umuarama) | |
| 1979.10.16 | Territorial Prelature of Pinheiro was promoted as Diocese of Pinheiro | |
| 1979.10.16 | Territorial Prelature of Ponta de Pedras was promoted as Diocese of Ponta de Pedras | |
| 1979.10.16 | Territorial Prelature of Porto Velho was promoted as Diocese of Porto Velho | |
| 1979.10.16 | Territorial Prelature of Roraima was promoted as Diocese of Roraima | |
| 1979.10.16 | Territorial Prelature of Rubiataba–Mozarlândia was promoted as Diocese of Rubiataba–Mozarlândia | |
| 1979.10.16 | Territorial Prelature of Santarém was promoted as Diocese of Santarém | |
| 1979.10.16 | Territorial Prelature of Santíssima Conceição do Araguaia was promoted as Diocese of Santíssima Conceição do Araguaia | |
| 1979.11.03 | Diocese of Belfort–Montbéliard was established (from Metropolitan Archdiocese of Besançon and became suffragan of Besançon) | |
| 1979.11.05 | Diocese of Cotabato was promoted as Metropolitan Archdiocese of Cotabato (with suffragan sees Kidapawan and Marbel) | |
| 1979.11.05 | Diocese of Digos was established (from Metropolitan Archdiocese of Davao and became suffragan of Davao) | |
| 1979.11.15 | Diocese of Meißen was renamed as Diocese of Dresden–Meißen | |
| 1979.12.24 | Territorial Prelature of Ipil was established (from Metropolitan Archdiocese of Zamboanga and became suffragan of Zamboanga) |
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