Appointed to the Legislative Council in May 2003 following a casual vacancy caused by the resignation of Diana Laidlaw, Lensink was elected for a further eight-year term at the 2006 election and has subsequently held a number of shadow ministerial positions including shadow responsibility for mental health and substance abuse, security and infrastructure, gambling, government enterprises, consumer affairs, environment and conservation, sustainability and climate change, the status for women, and for youth. She was re-elected for another eight-year term at the 2014 election. She was at third position on the Liberal ticket in both elections.