| 2003 NPB season | |
| League: | Nippon Professional Baseball |
| Sport: | Baseball |
| Duration: | March 28 - October 27, 2003 |
| Season: | Regular Season |
| Mvp: | CL Kei Igawa (HAN) |
| Mvp Link: | Nippon Professional Baseball Most Valuable Player Award |
| Playoffs: | League Postseason |
| Conf1: | CL |
| Conf1 Link: | Central League |
| Conf1 Champ: | Hanshin Tigers |
| Conf1 Runner-Up: | Chunichi Dragons |
| Conf2: | PL |
| Conf2 Link: | Pacific League |
| Conf2 Champ: | Fukuoka Daiei Hawks |
| Conf2 Runner-Up: | Seibu Lions |
| Finals: | Japan Series |
| Finals Link: | 2003 Japan Series |
| Finals Champ: | Fukuoka Daiei Hawks |
| Finals Runner-Up: | Hanshin Tigers |
| Finals Mvp: | Toshiya Sugiuchi (DAI) |
| Finals Mvp Link: | Japan Series Most Valuable Player Award |
| Seasonslist: | List of Nippon Professional Baseball seasons |
| Seasonslistnames: | NPB |
| Prevseason Link: | 2002 Nippon Professional Baseball season |
| Prevseason Year: | 2002 |
| Nextseason Link: | 2004 Nippon Professional Baseball season |
| Nextseason Year: | 2004 |
The Nippon Professional Baseball season ended with the Daiei Hawks defeating the Hanshin Tigers in the 2003 Japan Series 4 games to 3.
| Central League | G | W | L | T | Pct. | GB | |
|---|---|---|---|---|---|---|---|
| 140 | 87 | 51 | 2 | .629 | -- | ||
| 140 | 73 | 66 | 1 | .525 | 14.5 | ||
| 140 | 71 | 66 | 3 | .518 | 15.5 | ||
| 140 | 71 | 66 | 3 | .518 | 15.5 | ||
| 140 | 67 | 71 | 2 | .486 | 20.0 | ||
| 140 | 45 | 94 | 1 | .325 | 42.5 |
| Pacific League | G | W | L | T | Pct. | GB | |
|---|---|---|---|---|---|---|---|
| 140 | 82 | 55 | 3 | .596 | -- | ||
| 140 | 77 | 61 | 2 | .557 | 5.5 | ||
| 140 | 74 | 64 | 2 | .536 | 8.5 | ||
| 140 | 68 | 69 | 3 | .496 | 14.0 | ||
| 140 | 62 | 74 | 4 | .457 | 19.5 | ||
| 140 | 48 | 88 | 4 | .357 | 33.5 |