EFX may refer to:
- EFX (show), a Las Vegas show
- EFX (album), an album of the show
- Enterprise Framework (EFx), see EFx Factory
- Enerflex Systems, a Canadian company listed as EFX on the Toronto Stock Exchange
- Equifax, a U.S. company listed as EFX on the New York Stock Exchange
- Effects Extension (EFX), a set of digital signal processing extensions for the OpenAL audio API
- .efx, the Everett Efax file format, see List of file formats