Tomic competed at the Junior World Championships in 2006 and 2007. In 2007, Tomic set a world record in the 2000m pursuit in the under-19 age category. She also claimed three junior world titles. In 2008, she won her first senior national title, with a first-place finish in the 3000m individual pursuit with a time of 3:41.953. In November 2008, Tomic made an appearance at round 2 of the 2008–2009 UCI Track Cycling World Cup Classics in Melbourne, where she won silver in both the individual and team pursuit. On her senior World Championship debut on 28 March 2009, Tomic won the gold medal in the Omnium, the first time the competition had been included for women in the World Championships. She also won the bronze medal as a member of Australia's Team Pursuit squad. At the 2010 World Cup at Melbourne's Hisense Arena, she was part of an Australian team that won the country's first gold at the event. The medal was in the 3000m team pursuit. At the 2010 Commonwealth Games, she competed in the individual pursuit event where she finished fifth and in the points race where she finished tenth. She finished 4th in the team pursuit at the 2011 Track World Championships in Apeldoorn, Netherlands. She finished 1st in the individual pursuit at the 2011 Australian Track Championships in Sydney. She finished second in the team pursuit at the 2012 Track World Championships in Melbourne, Australia. She finished first in the team pursuit and 3rd in the individual pursuit at the 2012 Australian Championships in Adelaide. In the team pursuit event at the 2012 Summer Olympics Test Event in London, her team set the fastest time in the event on the opening day of the competition. Tomic was selected to represent Australia at the 2012 Summer Olympics in the Team Pursuit event. She was a member of the Australian track cycling team pursuit team that finished in fourth place at the 2012 Summer Olympics.