 Giannou scored his first goals for the club, a brace, in a 2–0 away victory against OFI on 11 February.On 2 September 2013 Panionios proceeded to a significant addition to its roster, by announcing the acquisition of Giannou.The 23-year-old striker was released by PAOK, as it was not in the plans of Huub Stevens, but did not stay for long time as unemployed and immediately signing a two-years' contract with the club.