From 1991 to 1994, Lensink worked as a physiotherapist at Repatriation General Hospital, Daw Park, before moving into the political arena.

[citation needed] In 2001, she was selected at number four on the Liberal Party's Senate ticket for the 2001 federal election; however, did not achieve the necessary quota.

[5] 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.

Since 26 January 2008, Lensink has also served as Deputy Leader of the Liberal Party in the Legislative Council.

[citation needed] In 2024, absent on sick leave due to cancer treatment, she paired with a fellow MLC to successfully vote down an anti-abortion bill (final result 9-10).