The 2005–06 ULEB Cup was the fourth season of the second-tier level European professional basketball competition ULEB Cup. The ULEB Cup is the level that is one tier below the Euroleague level. Dynamo Moscow won the trophy, by defeating Aris in the final, by a score of 73–60.
This season's ULEB Cup featured a total of 24 teams, divided into four groups of six. The round-robin group stage was followed by knock-out stages. The regular season began in October 2002.
Regular season
The 24 teams played a round-robin tournament competition (home and away). Four teams from each group advanced to the knock-out stage (quarter-finals).
Eighth-finals
The winners from eighth-finals advanced to the quarterfinals. The matches were played at two games (home and away). The match winner was determined by point differential.
Quarter-finals
The winners from quarter-finals advanced to the semifinals. The matches were played at two games (home and away). The match winner was determined by point differential.
Semifinals
The winners from semifinals advanced to the finals. The matches were played at two games (home and away). The match winner was determined by point differential.