At the 2010 European Championships, he won the gold medal in the 100 m with a time of 10.11 s. The next day, after comfortably progressing through the heats and semi-finals of the 200 m, Lemaitre became the double European champion by storming to victory in the 200 m final in a time of 20.37 s, beating Great Britain's Christian Malcolm by 0.01 s (Malcolm clocked his season's best time of 20.38 s in the final). Lemaitre then combined with Jimmy Vicaut, Pierre-Alexis Pessonneaux, and Martial Mbandjock in the 4 × 100 m relay final to finish first ahead of Italy and Germany in a time of 38.11 s. At the IAAF World Challenge's Rieti Meeting in Rieti, Italy on 29 August 2010, Lemaitre competed in the 100 m. In that event, he equalled his personal best in his heat with a time of 9.98 s, and improved on it in the final with a time of 9.97 s (reaction time 0.199 s).