Nicknamed Josie, Tomic was born on 9 June 1989 in Subiaco, Western Australia.

She started at Murdoch University in 2008 and was enrolled as of 2012, and was pursuing a Bachelor of Primary Education.

[3][4] 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.

[3] 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.

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.

[6] Tomic was selected to represent Australia at the 2012 Summer Olympics in the Team Pursuit event.