Kerr found employment as a fireman, but he was also an avid runner. He developed a name for himself and it wasn't long before he was known as the best sprinter in the region.
In 1904, Kerr travelled to Saint Louis in the United Stated to compete in the Summer Olympics. He was self funded, using his own savings to get to the games. He entered three events that year, the 60 metre, 100 metre, and 200 metre. Unfortunately it just wasn't his year, and he was elimimated in the heats of all three events.
Not one to be disheartened by failure, Kerr trained even harder and soon saw great improvements in his running. In 1908 he travelled to England where he competed in the British championships. There he came first in both the 100 and 200 yard races. That same year he returned to the Summer Olympics, this time held in London. He competed in the 100 and 200 metre races, placing in both.
When the First World War broke out, Kerr enlisted in the Canadian Expeditionary Force.
After completing his military service, Kerr returned to Hamilton where he remained highly involved in Athletics for the rest of his career. He worked as a coach and acted as an official in the 1928 and 1932 Summer Olympics.
Robert Kerr died on the 12th of May 1963 at the age of 80. He is commemorate by a public park bearing his name in Hamilton.