Obi started the "Milan Derby" at Beijing for the Supercoppa Italiana on 14 November but had to be substituted after only 35 minutes because of injury, he was replaced by Coutinho. In January 2011, Obi and Nwankwo Obiora were sold in co-ownership to Parma for just €750 and €300,000 respectively . However, Obi remained at Inter for the rest of the season, collecting 10 appearances in the league, two in Coppa Italia and one in the Champions League. In the league he was a starter under both Gian Piero Gasperini and the new coach, Claudio Ranieri. On 27 September he got his first start in the Champions League, and on 1 October, was sent for the first time in his career after a second yellow card at home to Napoli. On 17 January 2012 Parma sold their 50% share of Obi back to Inter for €3.2 million (€1.7 million plus Crisetig) and his salary was raised to a reported €600,000 per year. On 29 April, Obi scored his first goal in Serie A against Cesena, the momentary equaliser 1–1, in an eventual 2–1 victory. He concluded the 2011–12 season with 27 appearances in Serie A, two in Coppa Italia and seven in the Champions League, plus one in the final of Supercoppa Italiana. However, his season was cut short by a bad injury that restricted him to a long period of rest.
Obi made his international debut for Nigeria on 9 February 2011 in a friendly game with Sierra Leone in Lagos. He started the next 11 games in a row for the Eagles before getting injured near the end of 2012. He was named in the preliminary squad for the 2014 World Cup.