Snowsill won the 2000 International Triathlon Union World Championship in the 16–20 years age category plus the gold medal at the 2001 Sydney Youth Olympic Festival Triathlon at age 19. She was awarded a scholarship with the Australian Institute of Sport and was voted 16–19 years female Triathlete of the Year 2000. In 2003, Snowsill became ITU World Championfor the first time in Queenstown, New Zealand. In 2004, she won the ITU World Cup Championship and finished the season ranked first in the world. Despite this she was not selected for the Australian team for the 2004 Athens Olympics. In 2005, Snowsill took her second world crown in Gamagori, Japan, in temperatures and 90% relative humidity. During 2005 and 2006 she was the winner of the Lifetime Fitness Triathlon in Minneapolis. She won the gold medal at the 2006 Commonwealth Games in Melbourne. She won another gold medal at the 2006 World ITU Championships in Lausanne, where she finished 45 seconds in front of Portuguese triathlete Vanessa Fernandes. This made her the first female triathlete to win three world titles. The following year, in 2007, in Hamburg, Vanessa Fernandes won her first world title by beating Snowsill by over a minute. In 2008, Snowsill won the Mooloolaba World Cup season opener, beating her Olympic rival Fernandes. Snowsill skipped the ITU World Championships in order to devote all of energy to the 2008 Beijing Olympics. During the triathlon event she stayed with the leaders in the swim and cycle legs and broke clear in the run. Snowsill won the gold medal with a time of 1:58:27, 1 minute 7 seconds ahead of Fernandes. Fellow Australian Emma Moffatt won the bronze medal. Snowsill missed out on selection for the Australian London 2012 Olympic Triathlon Team. She appealed her omission but was turned down by the Tribunal. Snowsill decided not to take her case to the Court of Arbitration for Sport saying "Whilst I am upset with the outcome, I have to respect the decision of the Tribunal and will not be pursuing the matter further." Snowsill went on to wish the three selected women good luck for their race in London. During her career she has won the "Grand Slam" of Chicago, City of Los Angeles, London and New York Triathlons plus multiple ITU World Cup events.
