On 30 July, he appeared to break the 200 metres French national record, but it did not count as the wind speed was 2.3 m/s, which was 0.3 m/s over the limit. At the 2011 World Championships in Daegu, Lemaitre reached the final of the 100 m event, where he finished fourth. On September 3, he won the bronze medal in the 200 m event, with a time of 19.80 s and a wind speed of 0.8 m/s in the final. In doing so, he pulverized the previous French national record (20.16 s) that he had shared with Gilles Quénéhervé for 14 months by 0.36 second. In that race he became the second-fastest European 200 m sprinter in history after Pietro Mennea. On September 4, Lemaitre teamed up with Jimmy Vicaut, Teddy Tinmar and Yannick Lesourd to run a season best of 38.20 s in the 4 x 100 metres relay final, finishing second behind the world record-breaking Jamaican team and thus taking the silver medal.