| Competition: | Serie B TIM |
| Season: | 2002–03 |
| Promoted: | Siena (1st title) Sampdoria Lecce Ancona |
| Relegated: | Cosenza (bankruptcy) |
| League Topscorer: | Igor Protti (23 goals) |
| Matches: | 380 |
| Total Goals: | 961 |
| Longest Wins: | Vicenza 7 matches |
| Longest Unbeaten: | Vicenza 14 matches |
| Prevseason: | 2001–02 |
| Nextseason: | 2003–04 |
The 2002–03 Serie B was the 71st season since its establishment in 1929. It is the second highest football league in Italy.
Livorno, Ascoli, Triestina and Catania had been promoted from Serie C, while Hellas Verona, Lecce, and Venezia had been relegated from Serie A and Fiorentina had lost their national professional licence.
| Team | Manager | Kit manufacturer | Shirt sponsor | |
|---|---|---|---|---|
| Ancona |  Luigi Simoni | Devis | Banca Marche | |
| Ascoli | Giuseppe Pillon | Uhlsport | Carisap | |
| Bari | Marco Tardelli | Lotto | asbari.com | |
| Cagliari | Gian Piero Ventura | A-Line | Terra Sarda | |
| Catania | Vincenzo Guerini | Galex | SP Energia Siciliana | |
| Cosenza | Antonio Sala | Sport Point | Provincia di Cosenza | |
| Genoa | Rino Lavezzini and Vincenzo Torrente | Erreà | Costa Cruises | |
| Hellas Verona | Alberto Malesani | Lotto | Clerman | |
| Lecce | Delio Rossi | Asics | Salento d'amare | |
| Livorno | Roberto Donadoni | Asics | CR Livorno | |
| Messina | Bruno Bolchi | Asics | Jonax Group | |
| Napoli | Franco Colomba | Diadora | Peroni | |
| Palermo | Nedo Sonetti | Lotto | Provincia di Palermo | |
| Salernitana | Franco Varrella | Garman | Zip Jeans & Casual | |
| Sampdoria | Walter Novellino | Asics | Erg | |
| Siena | Giuseppe Papadopulo | Lotto | Monte Paschi Vita | |
| Ternana | Mario Beretta | Erreà | None | |
| Triestina | Ezio Rossi | Asics | Acegas | |
| Venezia | Gianfranco Bellotto | Sportika | Emmezeta | |
| Vicenza | Andrea Mandorlini | Biemme | Caffè Vero |
In June 2003, Catania was at the centre of a controversy that led to the enlargement of Serie B from 20 to 24 teams, known as Caso Catania. The club claimed that Siena fielded an ineligible player in a 1–1 tie, a result which saw Catania relegated, whereas the two extra points from a victory would have kept them safe. They were awarded a 2–0 victory before the result was reverted because the guilty player was a substitute which did not play the match, then Catania appealed to the judges of the Autonomous Region of Sicily who re-awarded the victory again. In August, the FIGC decided to let Catania, along with Genoa and Salernitana, stay in Serie B; the newly reborn Fiorentina were also added for the 2003–04 season. The ruling led to protests and boycotts by the other Serie B clubs that delayed the start of the season, until the intervention of the Italian government.