Petrovich was born in Bendigo, Victoria. She commenced her working life at her families business, Bynon Industries. Some of her community work involved being the marketing executive of the Central Victorian Racing Club and the Hanging Rock Racing Club. She was also very active in the local Liberal Party branches.
She won the Hanging Rock Ward in the Macedon Ranges Shire Council 2000 General Election on first preferences of 50.5%.[1] She again won this ward in the 2003 General Election on first preferences of 50.83%.[2] She served the council as deputy and then mayor during this period. She did not contest the 2005 council general election.
Prior to the 2006 Victorian state election, she won preselection for the second position on the Liberal ticket in Northern Victoria, with Shepparton'sWendy Lovell in the top position. In February 2008, she was appointed Shadow Parliamentary Secretary for Health Services.[3]
She was re-elected in the 2010 election, and was appointed Parliamentary Secretary for Sustainability and the Environment in the new coalition government.[4] She was also a Member of the Law Reform Committee.
Petrovich resigned from the Legislative Council on 1 July 2013 to contest the electorate of McEwen. She was defeated by incumbent Labor MP Rob Mitchell.
Petrovich also controversially nominated for the Liberal Party preselection contest for the South West Coast seat vacated by former premierDenis Napthine.[6] The endorsed Liberal Party candidate, and eventual winner of the by-election, Roma Britnell, defeated all other preselection candidates in the first round of voting, receiving more than 50% of the delegate votes.