The 2009–10 Euroleague was the 10th season of the professional basketball competition for elite clubs throughout Europe, organised by Euroleague Basketball Company, and it was the 53rd season of the premier competition for European men's clubs overall. The regular season featured 24 teams from 13 countries.

The EuroLeague, known as the Turkish Airlines EuroLeague for sponsorship reasons, is a European men's professional basketball club competition. The league is widely recognised as the top-tier men's league in Europe. The league consists of 18 teams, of which 16 are given long-term licences and wild cards, making the league a semi-closed league. The league was first organized by FIBA in 1958, subsequently by ULEB in 2000 and then solely the Euroleague Basketball.