Date | Country | Change |
| 902 |  Italy | Diocese of Nicotera was suppressed (to Diocese of Tropea) |
| 906 | Italy | Diocese of Taormina was suppressed |
| 909 |  England | Diocese of Crediton was established (from Diocese of Sherborne and became suffragan of Canterbury) |
| 909 | England | Diocese of Ramsbury was established (from Diocese of Dorchester and Diocese of Sherborne) |
| 909 | England | Diocese of Wells was established |
| 909 |  France | Abbacy nullius of Cluny was established |
| 910 | Italy | Diocese of Lilibeo was suppressed |
| 917 | Italy | Diocese of Vicenza lost territory to Diocese of Padova |
| 920 |  Spain | Diocese of Osma was suppressed |
| 922 | Spain | Diocese of Sasabe was established (from Diocese of Pamplona) |
| 923 | Spain | Diocese of Calahorra was suppressed (to establish Diocese of Nájera) |
| 923 | Spain | Diocese of Nájera was established (from the suppressed Diocese of Calahorra) |
| 927 |  Montenegro | Diocese of Bar was established (from the suppressed Metropolitan Archdiocese of Doclea) |
| 927 | Montenegro | Metropolitan Archdiocese of Doclea was suppressed (to Diocese of Ragusa and to establish Diocese of Bar) |
| 929 |  Croatia | Diocese of Nona was suppressed (to Diocese of Zadar) |
| 931 | England | Diocese of Cornwall was established (from Diocese of Crediton and became suffragan of Canterbury) |
| 934 |  Switzerland | Territorial Abbacy of Maria Einsiedeln was established |
| 940 | Italy | Diocese of Termoli was established |
| 940 | Italy | Diocese of Trivento was established |
| 944.05 | Italy | Diocese of Nomento was suppressed (to Diocese of Vescovìo) |
| 946.05.10 |  Germany | Diocese of Havelberg was established (became suffragan of Mainz) |
| 948 |  Denmark | Diocese of Ribe was established (from Metropolitan Archdiocese of Hamburg and became suffragan of Hamburg) |
| 948 | Denmark | Diocese of Århus was established (from Metropolitan Archdiocese of Hamburg and became suffragan of Hamburg) |
| 948 | Germany, Denmark | Diocese of Schleswig was established (from Metropolitan Archdiocese of Hamburg and became suffragan of Hamburg) |
| 948.10.01 | Germany | Diocese of Brandenburg was established (became suffragan of Mainz) |
| 950 | England | Diocese of Elmham was restored (became suffragan of Canterbury) |
| 950 | Italy | Diocese of Belcastro was established (from Metropolitan Archdiocese of Santa Severina and became suffragan of Santa Severina) |
| 950 | Italy | Diocese of Blanda was suppressed (to establish Diocese of Cassano all’Jonio) |
| 950 | Italy | Diocese of Cassano all’Jonio was established (from the suppressed Diocese of Blanda and Diocese of Thurio) |
| 950 | Italy | Diocese of Ferrara was established (from the suppressed Diocese of Voghenza and became suffragan of Milano) |
| 950 | Italy | Diocese of Plestia was restored (from Diocese of Camerino) |
| 950 | Italy | Diocese of Rossano was established (from the suppressed Diocese of Thurio and became suffragan of Reggio Calabria) |
| 950 | Italy | Diocese of Thurio was suppressed (to establish Diocese of Cassano all’Jonio and Diocese of Rossano) |
| 950 | Italy | Diocese of Voghenza was suppressed (to establish Diocese of Ferrara) |
| 950 | Spain | Diocese of Segovia was suppressed |
| 950 | Spain | Diocese of Urci was suppressed |
| 952 | Germany | Diocese of Oldenburg was established (from Metropolitan Archdiocese of Hamburg and became suffragan of Hamburg) |
| 953 | Spain | Diocese of Simancas was established (from Diocese of Astorga and Diocese of León) |
| 956 | Italy | Archdiocese of Otranto was promoted as Metropolitan Archdiocese of Otranto (with suffragan sees Acerenza and Alessano) |
| 956 | Spain | Diocese of Pallars–Ribagorça was renamed as Diocese of Roda (gained territory from Diocese of Urgell) |
| 956 | Spain | Archdiocese of Tarragona was restored (became suffragan of Narbonne) |
| 956 | Spain,  Andorra | Diocese of Urgell lost territory to Diocese of Roda |
| 960 | Italy | Diocese of Ariano was established |
| 960 | Italy | Diocese of Atina was established (from Diocese of Sora) |
| 960 | Italy | Diocese of Cerenza was established |
| 966.08.14 | Italy | Diocese of Caiazzo was established (became suffragan of Capua) |
| 966.08.14 | Italy | Diocese of Capua was promoted as Metropolitan Archdiocese of Capua (with suffragan sees Aquino, Atina, Caiazzo, Calvi, Fondi, Forum claudii, Gaeta, Sessa Aurunca, Sora and Teano) |
| 968 | Germany | Metropolitan Archdiocese of Magdeburg was established (from Diocese of Halberstadt and with suffragan sees Brandenburg, Havelberg, Meißen, Merseburg and Zeitz) |
| 968 | Germany | Diocese of Meißen was established (became suffragan of Magdeburg) |
| 968 | Germany | Diocese of Merseburg was established (became suffragan of Magdeburg) |
| 968 | Germany | Diocese of Zeitz was established (became suffragan of Magdeburg) |
| 968 | Italy | Diocese of Tricarico was established (became suffragan of Otranto) |
| 968 | Italy | Diocese of Tursi was established |
| 968 |  Poland | Diocese of Poznań was established |
| 969.05.26 | Italy | Diocese of Ascoli Satriano was established (from Diocese of Benevento and became suffragan of Benevento) |
| 969.05.26 | Italy | Diocese of Benevento was promoted as Metropolitan Archdiocese of Benevento (with suffragan sees Alife, Ariano, Ascoli Satriano, Avellino, Eclena, Larino, Sant’Agata de’ Goti, Siponto and Telese and lost territory to establish Diocese of Ascoli Satriano and Diocese of Sant’Agata de’ Goti) |
| 969.05.26 | Italy | Diocese of Sant’Agata de’ Goti was established (from Diocese of Benevento and became suffragan of Benevento) |
| 969.08.10 | Italy | Diocese of Asolo was suppressed (to Diocese of Padova, Diocese of Treviso and Diocese of Vicenza) |
| 970 | Italy | Diocese of Bovino was restored (from Metropolitan Archdiocese of Benevento and became suffragan of Benevento) |
| 970 | Italy | Diocese of Norma was suppressed (to Diocese of Velletri) |
| 970 | Italy | Diocese of Taranto was promoted as Metropolitan Archdiocese of Taranto |
| 971 | England | Diocese of Dorchester was renamed as Diocese of Dorchester |
| 973 |  Czechia | Diocese of Praha was established (from Diocese of Regensburg and became suffragan of Mainz) |
| 974 | Spain | Diocese of Simancas was suppressed (to Diocese of Astorga and Diocese of León) |
| 981 | Germany | Diocese of Merseburg was suppressed (to Metropolitan Archdiocese of Magdeburg) |
| 983.06 | Italy | Diocese of Salerno was promoted as Metropolitan Archdiocese of Salerno (with suffragan sees Acerenza, Bisignano, Conza, Cosenza, Malvito, Nola and Pesto) |
| 984 |  Bosnia and Herzegovina | Diocese of Trebinje was established (from Diocese of Ragusa) |
| 984 | Germany | Abbacy nullius of St. Stephanus und Vitus in Corvey was established |
| 984 | Italy | Diocese of Lavello was established |
| 987.02.13 | Italy | Diocese of Amalfi was promoted as Metropolitan Archdiocese of Amalfi (with suffragan sees Capri, Lettere, Minori and Scala and lost territory to establish Diocese of Capri, Diocese of Lettere, Diocese of Minori and Diocese of Scala) |
| 987.02.13 | Italy | Diocese of Capri was established (from Diocese of Amalfi and became suffragan of Amalfi) |
| 987.02.13 | Italy | Diocese of Lettere was established (from Diocese of Amalfi and became suffragan of Amalfi) |
| 987.02.13 | Italy | Diocese of Minori was established (from Diocese of Amalfi and became suffragan of Amalfi) |
| 987.02.13 | Italy | Diocese of Scala was established (from Diocese of Amalfi and became suffragan of Amalfi) |
| 988 | Denmark | Diocese of Odense was established (from Diocese of Schleswig and became suffragan of Hamburg) |
| 989 | Spain | Diocese of Zamora was suppressed |
| 990 | Italy | Diocese of Vieste was established (from Diocese of Siponto) |
| 991 | Denmark | Diocese of Roskilde was established (from Metropolitan Archdiocese of Hamburg and became suffragan of Hamburg) |
| 992 | Germany | Diocese of Mecklenburg was established (from Metropolitan Archdiocese of Hamburg and became suffragan of Hamburg) |
| 992 | Italy | Diocese of Vado Ligure was renamed as Diocese of Savona |
| 995 | England | Diocese of Cunecaster was suppressed (to establish Diocese of Durham) |
| 995 | England | Diocese of Durham was established (from the suppressed Diocese of Cunecaster and became suffragan of York) |
| 996 | Italy | Diocese of Eraclea was restored (from Diocese of Belluno) |
| 996 | Poland | Diocese of Kujawy–Pomorze was established |
| 997 |  Hungary | Territorial Abbacy of Pannonhalma was established (without ecclesiastical province) |
| 999 | Poland | Metropolitan Archdiocese of Gniezno was established (from Diocese of Poznań and with suffragan sees Kołobrzeg and Wrocław) |
| 999 | Poland | Diocese of Kołobrzeg was established (became suffragan of Gniezno) |
| 999 | Poland | Diocese of Wrocław was established (from Diocese of Meißen and Diocese of Praha and became suffragan of Gniezno) |
| 999.01.07 | Italy | Diocese of Treviso lost territory to Diocese of Eraclea |
| 1000 |  Albania | Diocese of Dagno was established |
| 1000 | Albania | Diocese of Hadrianopolis in Epiro was suppressed |
| 1000 |  Greece | Diocese of Corfù was suppressed |
| 1000 | Greece | Diocese of Corone was established |
| 1000 | Greece | Diocese of Kisamos was established |
| 1000 |  Ireland | Diocese of Limerick was established (became suffragan of Canterbury) |
| 1000 | Italy | Diocese of Acquaputrida was established (became suffragan of Benevento) |
| 1000 | Italy | Diocese of Biccari was established (became suffragan of Benevento) |
| 1000 | Italy | Diocese of Bitonto was established (became suffragan of Bari) |
| 1000 | Italy | Diocese of Città della Pieve was established (without ecclesiastical province) |
| 1000 | Italy | Diocese of Gravina was suppressed |
| 1000 | Italy | Diocese of Minturno was suppressed (to Diocese of Gaeta) |
| 1000 | Italy | Diocese of Montepeloso was established |
| 1000 | Italy | Diocese of Napoli was promoted as Metropolitan Archdiocese of Napoli (with suffragan see Pozzuoli) |
| 1000 | Italy | Diocese of Norcia was suppressed (to Diocese of Spoleto) |
| 1000 | Italy | Diocese of Rossano was promoted as Archdiocese of Rossano |
| 1000 | Italy | Abbacy nullius of Sacra di San Michele was established |
| 1000 | Italy | Abbacy nullius of San Pietro di Novalesa was established (from Diocese of Torino) |
| 1000 | Italy | Abbacy nullius of Santa Maria di Sesto was established |
| 1000 | Italy | Abbacy nullius of Santa Maria di Vangadizza was established |
| 1000 | Italy | Diocese of Sarno was established (became suffragan of Salerno) |
| 1000 | Italy | Diocese of Sinis-Tharros was promoted as Metropolitan Archdiocese of Sinis-Tharros |
| 1000 | Italy | Diocese of Tocco Caudio was established (became suffragan of Benevento) |
| 1000 | Italy | Diocese of Trevico was established (became suffragan of Benevento) |
| 1000 |  North Macedonia | Metropolitan Archdiocese of Acrida was established (with suffragan see Prizren) |
| 1000 | Spain | Diocese of Basti was suppressed |
| 1000 | Spain | Diocese of Cartagena–Bigastro was suppressed |
| 1000 | Spain | Diocese of Coria was suppressed |
| 1000 | Spain | Diocese of Córdoba was suppressed |
| 1000 | Spain | Diocese of Écija was suppressed |
| 1000 |  Syria | Diocese of Philippopolis was suppressed |
| 1000 |  Tunisia | Metropolitan Archdiocese of Carthage was suppressed |
| 1000 |  Turkiye | Metropolitan Archdiocese of Antiochia was suppressed |
| 1000 | Turkiye | Diocese of Comana Ponti was suppressed |
| 1000 | Turkiye | Metropolitan Archdiocese of Ephesus was suppressed |
| 1000 | Turkiye | Metropolitan Archdiocese of Hierapolis was suppressed |
| 1000 | Turkiye | Diocese of Nyssa was suppressed |
| 1000 | Turkiye | Diocese of Samosata was suppressed |
| 1000.03.08 | Poland | Diocese of Kraków was established (became suffragan of Gniezno) |
