Gerald Phiri made his Olympian debut at the age of 23. He qualified for the Games because his personal best time of 10.06 seconds for the men's 100 metres, set at the 2011 Texas Relays, exceeded the "A" standard qualifying entry time. In preparation for the event, he trained with his coach in the Netherlands while adapting to a different climate and a new time zone. Phiri received a bye to advance beyond the preliminary round. He competed in the first heat of the first round on 4 August, finishing third out of eight athletes with a time of 10:16 seconds qualifying for the semi-finals. In the semi-finals on 5 August, Phiri achieved a fifth-place finish in heat two with a time of 10:11 seconds, which was his best of the 2012 athletic season. Overall he finished 15th out of 75th athletes overall and was unable to progress further because his time was 0.09 seconds slower than the slowest qualifying finalist. After the event Phiri said he placed a large amount of pressure onto himself but was not good enough in the event. Nevertheless, he thanked his supporters.