| Aïn Defla Province | |
| Native Name: | ولاية عين الدفلى |
| Native Name Lang: | ar |
| Type: | Province |
| Map Caption1: | Map of the 14 districts of Aïn Defla |
| Coordinates: | 36.3167°N 12°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Algeria |
| Seat Type: | Capital |
| Seat: | Aïn Defla |
| Leader Title: | PPA president |
| Leader Name: | Mr. Menad Mehdi (FLN) |
| Leader Title1: | Wāli |
| Leader Name1: | Mr. Tikhmarine Lakhdar |
| Unit Pref: | Metric |
| Area Total Km2: | 4897 |
| Population Footnotes: | [1] |
| Population Total: | 771890 |
| Population As Of: | 2008 |
| Population Density Km2: | auto |
| Timezone1: | CET |
| Utc Offset1: | +01 |
| Iso Code: | DZ-44 |
| Area Code Type: | Area Code |
| Area Code: | +213 (0) 27 |
| Blank Name Sec1: | Districts |
| Blank Info Sec1: | 14 |
| Blank1 Name Sec1: | Municipalities |
| Blank1 Info Sec1: | 36 |
Aïn Defla (Arabic: ولاية عين الدفلى, is a wilaya (province) in northern Algeria. It is located to the southwest of Algiers, the capital. Localities in Ain Delfa include Aïn Defla, Miliana, El Attaf, Djelida and Djendel.
The province was created from Chlef Province in 1984.
It is made up of 14 districts and 36 municipalities.
The districts are:
The municipalities are: