On 31 August 2011, Zárate completed a loan deal from Lazio to Inter Milan with a view to a permanent transfer. On 27 September 2011, he scored a 79th-minute winner, his first goal for the club, in an away match against CSKA Moscow in the group stage of the 2011–12 UEFA Champions League. His first Serie A goal for Inter did not come until 1 April 2012, when he scored their fourth goal, a "spectacular curling right-footed shot" in a 5–4 win against Genoa. He finished the 2011–12 season with 3 goals from 29 appearances in all competitions.