He soon became the best regional sprinter, and in 1904 he used his savings to travel to Saint Louis, United States and compete in the 1904 Summer Olympics.

[3][4] At the 1908 Summer Olympics, held in London, Kerr was considered to be somewhat of a home favourite by the crowd, as they saw him as a representative of the British Empire.

In the 100 metres, he finished in third (behind South Africa's Reggie Walker and the United States' James Rector) with a time of 11.0 seconds.

In the final of the 200 metres, held the next day, Kerr crossed the line first with a time of 22.6 seconds.

Furthermore, he was involved in the Canadian Olympic Association, and helped organize the 1930 British Empire Games in Hamilton.