In August 2005, he returned to the Serie A with a transfer to Internazionale on a four-year contract for reported €16 million fee. He began his Inter adventure by winning the 2005 Supercoppa Italiana versus Juventus, entering in 63rd minute as "Nerazzurri" won at extra-time thanks to the winner of Verón. Later on 13 September, he made his league debut for his new side on 21 September by starting in the 1–0 away win over Chievo. On 24 November, during a Champions League group stage match against Petržalka, Samuel played in a line-up of 11 foreign players on the pitch, with Luís Figo being the only european. He finished his first season at Inter by making 42 appearances in all competitions, with the team winning the championship following the relegation of Juventus due to match-fixing, and Coppa Italia by defeating Roma 4–2 on aggregate, with Samuel playing on both finals, thus completing an unforeseen domestic treble.