| Jurisdiction: | Archdiocese |
| Alba Iulia | |
| Latin: | Archidioecesis Albae Iuliensis |
| Local: | Arhiepiscopia de Alba Iulia |
| Country: |  Romania |
| Metropolitan: | Immediately Subject to the Holy See |
| Area Km2: | 58,254 |
| Population: | 4,017,256 |
| Population As Of: | 2015 |
| Catholics: | 397,778 |
| Catholics Percent: | 9.9 |
| Parishes: | 253 |
| Rite: | Roman Rite |
| Established: | 1009 (As Diocese of Transilvania, Erdély, Siebenbürgen) 22 March 1932 (As Diocese of Alba Iulia) 5 August 1991 (Archdiocese of Alba Iulia) |
| Cathedral: | St. Michael's Cathedral, Alba Iulia |
| Bishop: | Gergely Kovács |
| Bishop Title: | Archbishop |
| Suffragan: | for one --> |
| Auxiliary Bishops: | László Kerekes (elect) |
| Archdeacon: | for one--> |
| Map: | Romanian Roman-Catholic Church map.svg |
| Map Size: | 250px |
The Roman Catholic Archdiocese of Alba Iulia (Latin: Archidioecesis Albae Iuliensis); Hungarian: Gyulafehérvári Római Katolikus Érsekség) is a Latin Church archdiocese in Transylvania, Romania.
It was established as a bishopric, the diocese of Transylvania also called Erdély (in Hungarian), or Karlsburg alias Siebenbürgen (in German), in 1009 by King Stephen I of Hungary and was renamed as the diocese of Alba Iulia on 22March 1932. It was raised to the rank of an archdiocese by Pope John Paul II on 5August 1991. It is exempt, i.e. directly subordinate to the Vatican, while the other Romanian dioceses form the Ecclesiastical Province of Bucharest.
The archdiocese covers Transylvania proper - the counties of Alba, Bistrița-Năsăud, Brașov, Cluj, Covasna, Harghita, Hunedoara, Mureș, Sălaj and Sibiu.
The cathedral episcopal see is St. Michael's, in Alba Iulia city. It also has a minor basilica in Șumuleu Ciuc.
11% of the inhabitants are Roman Catholic, with concentrations in parts of Harghita and Covasna counties. Catholic adherents are predominantly ethnic Hungarians.