Larkham's parents owned a tennis center and both worked as tennis coaches. Both Todd and his two year younger brother Brent were therefore introduced to tennis from childhood. In 1993 he became a professional tennis player and mostly played at tournaments on the ATP Challenger Tour . In 1992 he won the Challenger tournament in Olbia on the side of the Briton Chris Wilkinson . He won his second and last double title in Grenoble with his compatriot Michael Tebbutt . He won his only individual title in 2003 in Scheveningen by beating Diego Veronelli in the final . At tournaments of the ATP World Tour he usually failed in qualifying, a notable exception was the Bournemouth Open 1998, when he won against Miles Maclagan and lost to Stefan Koubek in the second round .
In the course of his career he was able to win a single title and two double titles on the Challenger Tour. He reached his highest ranking in the tennis world rankings in 2003 with position 136 in singles and in 1998 with position 168 in doubles.
His best individual result in a Grand Slam tournament was reaching the second round at the Australian Open 2003, where he lost to Lleyton Hewitt after three qualifying rounds and his first round win against Cecil Mamiit in the second round . He wasn't particularly lucky in Grand Slam tournaments, he met Andre Agassi , Tim Henman and Pete Sampras in his first round games . In the doubles competition he reached the second round of the Australian Open in 1996 and 1998.
Australia
Scheveningen
Diego Veronelli
Olbia
Chris Wilkinson
Thomas Shimada Filippo Veglio
Grenoble