The 2009–10 UEFA Champions League was the 55th season of Europe's premier club football tournament organised by UEFA, and the 18th under the current UEFA Champions League format. The final was played on 22 May 2010 at the Santiago Bernabéu Stadium in Madrid, Spain, the first time the final was played on a Saturday. The final was won by Italian club Inter Milan, who beat German side Bayern Munich 2–0.

Inter Milan went on to represent Europe in the 2010 FIFA Club World Cup, beating Congolese side TP Mazembe 3–0 in the final, and played in the 2010 UEFA Super Cup against Europa League winners Atlético Madrid, losing 2–0.

Barcelona were the defending champions, but they were eliminated by eventual winners Inter Milan in the semi-finals.

A total of 76 teams participated in the 2009–10 Champions League, from 52 UEFA associations (Liechtenstein organises no domestic league competition). Associations were allocated places according to their 2008 UEFA country coefficient, which took into account their performance in European competitions from 2003–04 to 2007–08.

Below is the qualification scheme for the 2009–10 UEFA Champions League:

Since the winners of the 2008–09 UEFA Champions League, Barcelona, obtained a place in the group stage through their domestic league placing, the reserved title holder spot in the group stage was effectively vacated. To compensate:

The labels in the parentheses show how each team qualified for the place of its starting round:

All draws held at UEFA headquarters in Nyon, Switzerland unless stated otherwise.