On 16 July 2009, Lúcio moved to Italian club Inter Milan, signing a three-year contract with the Serie A champions. He was given the number 6 shirt. He scored his first goal with Inter on 23 September 2009 against Napoli with a header from a corner kick. Lúcio also scored an own goal in the UEFA Champions League in the group stages against Dynamo Kyiv, resulting in a draw. Throughout the season, both Lúcio and his defensive partner Walter Samuel drew praise for their performances, and on 22 May, Lúcio was in the Inter team that won the Champions League by defeating his former club Bayern Munich 2–0, to seal a historic treble and end a 45-year wait to be crowned European Champions. On 24 September 2011, Lúcio made his 100th appearance in an Inter shirt, scoring the third of a 3–1 win at Bologna in Serie A matchday 5. On 29 June 2012, it was announced that Lúcio would be leaving Inter following a mutual agreement to terminate the final two years of his contract.