The word Atchafalaya derives from the Choctaw term hacha falaia, meaning "long river".
Atchafalaya may refer to:
- Atchafalaya, Louisiana, Ghost town in Louisiana, U.S.
- Atchafalaya River, Louisiana, U.S.
- Atchafalaya Basin or Atchafalaya Swamp, wetlands surrounding the lower part of the Atchafalaya River, Louisiana
- Atchafalaya Basin Bridge
- Atchafalaya Swamp Freeway, a portion of Interstate 10 in Louisiana that includes the bridge
- Atchafalaya National Heritage Area
- Atchafalaya National Wildlife Refuge
- Atchafalaya Basin or Atchafalaya Swamp, wetlands surrounding the lower part of the Atchafalaya River, Louisiana
- Atchafalaya Golf Course at Idlewild, Patterson, Louisiana
- A song from the album Sylva, by jazz ensemble Snarky Puppy