Kerr won in his career so far nine titles on the ATP World Tour and was in addition to six other finals. A total of five times he won the tournament in Newport, making its record winner in the doubles competition. On the second-rate Challenger Tour Kerr won so far even 20 tracks. At Grand Slam tournaments he pulled in double several times a last sixteen. In the Mixed competitions he reached the semifinals at Wimbledon in 2003. His highest ATP singles ranking was room 356, which he reached on 7 August 2000, he won third place in a double 25 on October 8, 2007.
2008 Kerr represented his country at the Olympic Games in Beijing, where he competed in the doubles competition. However, when combined with Paul Hanley he lost already in the opening round against the Swedes Simon Aspelin and Thomas Johansson with 6:7, 3:6.