| Jurisdiction: | Diocese |
| Avellaneda-Lanús | |
| Latin: | Dioecesis Avellanediensis-Lanusensis |
| Local: | Diócesis de Avellaneda-Lanús |
| Country: |  Argentina |
| Metropolitan: | Buenos Aires |
| Province: | Buenos Aires |
| Area Km2: | 98 |
| Population: | 794,485 |
| Population As Of: | 2012 |
| Catholics: | 635,588 |
| Catholics Percent: | 80 |
| Parishes: | 50 |
| Denomination: | Roman Catholic |
| Rite: | Roman Rite |
| Established: | 10 April 1961 (years ago) |
| Cathedral: | Cathedral of the Assumption in Avellaneda |
| Patron: | St Teresa of Ávila Assumption of Mary |
| Bishop Title: | Bishop |
| Bishop: | Marcelo Julián Margni |
| Metro Archbishop: | Mario Aurelio Poli |
| Emeritus Bishops: | Rubén Oscar Frassia |
The Latin Rite Catholic Diocese of Avellaneda-Lanús (erected 10 April 1961, as the Diocese of Avellaneda) is in Argentina and is a suffragan of the Archdiocese of Buenos Aires. It was renamed on 24 April 2001.
| Year | Along with | To form | |
|---|---|---|---|
| 1976 | Archdiocese of La Plata | Diocese of Quilmes |