04 may refer to
- The year 2004, or any year ending with 04
- The month of April
- 4 (number)
- 04 (Six by Seven album)
- 04 (Urban Zakapa album)
- 04, department number of Alpes-de-Haute-Provence, France
- Several German football teams, e.g. Bayer 04 Leverkusen, FC Ingolstadt 04, 1. FC Neubrandenburg 04, FC Schalke 04
- The prefix for mobile phones in Australia