The 2002–03 ULEB Cup was the inaugural season of Europe's secondary level professional club basketball tournament, the ULEB Cup, which is organised by Euroleague Basketball.

As the winners of the 2002–03 ULEB Cup, Valencia qualified for the European top-tier level 2003–04 Euroleague.

A total of 24 teams from 10 countries, instead of the initial 32, participated in the 2002–03 ULEB Cup.

The inaugural ULEB Cup also didn't feature teams from Greece, Lithuania and Israel as they chose to play in FIBA's competition.

[1] League positions after Playoffs of the previous season shown in parentheses:[2][3] The schedule of the competition was as follows.