| Competition: | 1. divisjon |
| Season: | 2003 |
| Dates: | 13 April – 1 November |
| Winners: | HamKam |
| Promoted: | HamKam Fredrikstad |
| Relegated: | Bærum Manglerud Star Ørn-Horten Alta |
| Matches: | 240 |
| Total Goals: | 820 |
| League Topscorer: | Markus Ringberg (19 goals) |
| Prevseason: | 2002 |
| Nextseason: | 2004 |
The 2003 1. divisjon season kicked off on 13 April 2003, and the final round was played on 1 November 2003.
Ham-Kam were promoted to the 2004 Tippeligaen as 1. divisjon winners, along with Fredrikstad who finished second. Ham-Kam will be playing in the top division for the first time since 1995, while Fredrikstad returned for the first time since 1975.
As in previous seasons, there was a two-legged promotion play-off at the end of the season, between the third-placed team in the 1. divisjon (Sandefjord) and the twelfth-placed team in the Tippeligaen (Vålerenga). Vålerenga kept their spot in the Tippeligaen, beating Sandefjord 5-3 on aggregate.
| Rank | Scorer | Club | Goals |
|---|---|---|---|
| 1 |  Markus Ringberg | HamKam | 19 |
| 2 | Christian Johnsen | Raufoss | 17 |
| 3 |  Haraldur Ingólfsson | Raufoss | 15 |
| 4 | Ben Wright | Start | 13 |
| Geir Televik | Hødd | ||
| Tom Helge Jacobsen | Sandefjord |