Date | Country | Change |
| 1930 |  Albania | Titular Episcopal See of Croæ was renamed as Titular Episcopal See of Croæ |
| 1930 |  Bulgaria | Titular Metropolitan See of Preslavus was established |
| 1930 |  Egypt | Titular Episcopal See of Nitrium was suppressed |
| 1930 |  Germany | Diocese of Fulda lost territory to Diocese of Hildesheim |
| 1930 |  Greece | Titular Episcopal See of Milopotamus was renamed as Titular Episcopal See of Eleutherna |
| 1930 |  Norway | Titular Episcopal See of Selja was restored |
| 1930 |  Romania | Apostolic Administration of Targul-Siret (Ruthenian Rite) was suppressed |
| 1930 |  Syria | Titular Episcopal See of Abila was renamed as Titular Episcopal See of Abila Lysaniæ |
| 1930 | Syria | Titular Episcopal See of Neve was renamed as Titular Episcopal See of Neve |
| 1930 |  Tunisia | Titular Episcopal See of Abbirmajus was renamed as Titular Episcopal See of Abbir majus |
| 1930 |  Turkiye | Titular Episcopal See of Adana was promoted as Titular Archiepiscopal See of Adana |
| 1930 | Turkiye | Titular Episcopal See of Bahtnæ (Syriac Rite) was renamed as Titular Episcopal See of Bahtnæ |
| 1930 | Turkiye | Titular Episcopal See of Flaviopolis was renamed as Titular Episcopal See of Cratia |
| 1930 | Turkiye | Titular Archiepiscopal See of Rhizæum was renamed as Titular Archiepiscopal See of Rhizæum |
| 1930 | Turkiye | Titular Episcopal See of Theodosiopolis was renamed as Titular Episcopal See of Theodosiopolis |
| 1930 | | Titular Episcopal See of Charadrus was suppressed |
| 1930.01.25 | Albania | Diocese of Sapë exchanged territory with Metropolitan Archdiocese of Shkodrë |
| 1930.01.25 | Albania | Metropolitan Archdiocese of Shkodrë exchanged territory with Diocese of Sapë |
| 1930.01.25 |  China | Apostolic Prefecture of Pingliang 平涼 was established (from Apostolic Vicariate of Qinzhou 秦州) |
| 1930.01.27 |  Bolivia | Apostolic Vicariate of Chiquitos was established (from Diocese of Santa Cruz de la Sierra) |
| 1930.01.31 |  Canada | Diocese of Gravelbourg was established (from Metropolitan Archdiocese of Regina and became suffragan of Regina) |
| 1930.02.12 |  Australia | Diocese of Townsville was established (from Diocese of Rockhampton and became suffragan of Brisbane) |
| 1930.02.14 | China | Mission sui juris of Xinjiang 新疆 was restored (from Apostolic Vicariate of Lanchowfu 蘭州府) |
| 1930.02.19 |  Ecuador | Apostolic Prefecture of Canelos y Macas was renamed as Apostolic Prefecture of Canelos |
| 1930.03.30 | Greece | Diocese of Santorini lost territory to Archdiocese of Rhodes |
| 1930.03.30 |  South Africa | Apostolic Prefecture of Umtata was established (from Apostolic Vicariate of Mariannhill) |
| 1930.05.26 |  India | Diocese of Kottar was established (from Diocese of Quilon and became suffragan of Verapoly) |
| 1930.05.26 | India | Diocese of Salem was established (from Metropolitan Archdiocese of Pondicherry, Diocese of Kumbakonam and Diocese of Mysore and became suffragan of Pondicherry) |
| 1930.05.31 | China | Apostolic Prefecture of Wuchang 武昌 was promoted as Apostolic Vicariate of Wuchang 武昌 |
| 1930.05.31 |  Colombia | Apostolic Prefecture of Caquetá was promoted as Apostolic Vicariate of Caquetá |
| 1930.05.31 |  Papua New Guinea | Apostolic Prefecture of Northern Solomon Islands was promoted as Apostolic Vicariate of Northern Solomon Islands |
| 1930.06.05 | Romania | Diocese of Gherla, Armenopoli, Szamos-Ujvár (Romanian Rite) was renamed as Diocese of Cluj–Gherla (lost territory to establish Diocese of Maramureş) |
| 1930.06.05 | Romania | Diocese of Maramureş (Romanian Rite) was established (from Metropolitanate sui juris of Făgăraş şi Alba Iulia, Diocese of Gherla, Armenopoli, Szamos-Ujvár, Diocese of Hajdúdorog, Diocese of Ivano-Frankivsk, Diocese of Mukačeve and Diocese of Oradea Mare and became suffragan of Făgăraş şi Alba Iulia) |
| 1930.06.05 | Romania | Ordinariate of Romania (Armenian Rite) was established |
| 1930.06.05 | Romania | Apostolic Administration of Timişoara was promoted as Diocese of Timişoara |
| 1930.06.05 |  Ukraine | Metropolitan Archdiocese of Lviv lost territory to Diocese of Iaşi |
| 1930.06.06 | Romania | Archdiocese of Bucureşti was promoted as Metropolitan Archdiocese of Bucureşti (with suffragan sees Iaşi, Oradea Mare, Satu Mare, Timişoara and Transilvania) |
| 1930.06.30 | China | Mission sui juris of Wuzhou 梧州 was established (from Apostolic Vicariate of Nanning 南寧) |
| 1930.06.30 |  Thailand | Mission sui juris of Rajaburi was established (from Apostolic Vicariate of Bangkok) |
| 1930.07.04 |  Eritrea | Ordinariate of Eritrea (Eritrean Rite) was established |
| 1930.07.14 |  Congo-Kinshasa | Apostolic Prefecture of Matadi was promoted as Apostolic Vicariate of Matadi |
| 1930.07.14 | India | Diocese of Vijayapuram was established (from Metropolitan Archdiocese of Verapoly and became suffragan of Verapoly) |
| 1930.07.14 |  Namibia | Apostolic Prefecture of Great Namaqualand was promoted as Apostolic Vicariate of Great Namaqualand |
| 1930.07.23 | China | Apostolic Vicariate of Hengzhou 衡州 was established (from Apostolic Vicariate of Changsha 長沙) |
| 1930.08.01 |  USA | Diocese of Lead was suppressed (to establish Diocese of Rapid City) |
| 1930.08.01 | USA | Diocese of Rapid City was established (from the suppressed Diocese of Lead and became suffragan of Saint Paul) |
| 1930.08.13 | Germany | Diocese of Aachen was restored (from Metropolitan Archdiocese of Köln and Diocese of Münster and became suffragan of Köln) |
| 1930.08.13 | Germany | Diocese of Berlin was established (from Diocese of Wrocław and became suffragan of Wrocław) |
| 1930.08.13 | Germany | Diocese of Fulda lost territory to Diocese of Limburg |
| 1930.08.13 | Germany | Apostolic Vicariate of North German Missions was suppressed (to Metropolitan Archdiocese of Paderborn and Diocese of Osnabrück) |
| 1930.08.13 | Germany | Diocese of Paderborn was promoted as Metropolitan Archdiocese of Paderborn (with suffragan sees Fulda and Hildesheim, gained territory from the suppressed Apostolic Vicariate of North German Missions and lost territory to Metropolitan Archdiocese of Köln and Diocese of Fulda) |
| 1930.08.13 | Germany,  Denmark | Apostolic Prefecture of Schleswig-Holstein was suppressed (to Diocese of Osnabrück) |
| 1930.08.13 |  Poland | Diocese of Chełmno lost territory to Diocese of Warmia |
| 1930.08.13 | Poland | Apostolic Administration of Tütz was promoted as Territorial Prelature of Schneidemühl (became suffragan of Wrocław) |
| 1930.08.13 | Poland | Diocese of Wrocław was promoted as Metropolitan Archdiocese of Wrocław (with suffragan sees Berlin, Warmia and Schneidemühl and lost territory to establish Diocese of Berlin) |
| 1930.11.14 | USA | Diocese of Oklahoma was renamed as Diocese of Oklahoma City–Tulsa |
