Penny has been a Member of the NSW Legislative Council since October 2005. In November 2018, Penny was elected Deputy Leader of the Labor Party.
Penny has previously served as the Parliamentary Secretary for Transport and the Parliamentary Secretary for Mining and Energy. Penny has served as the Attorney General's representative to the NSW Privacy Advisory Committee and has sat on a number of committees including Legislation Review, Privileges, Electoral Matters and the Joint Committee for Children and Young People.
Penny’s policy interests include: education (early childhood, vocational education & training, skills development, and schools), affordable housing (private, community and public), improving democracy through technology, mining and energy, maternity services, women (choice, violence, and power), children (rights and out of home care), drug and alcohol policy, human rights, indigenous issues, GLBT policies, crime prevention, community development and prisons.
Prior to entering parliament, Penny worked as a policy advisor to state ministers, designed workplace learning programs for young people and was the President of the National Union of Students. She also served as a Councillor on Marrickville Council from 2004 to 2008.
Penny has been a foster carer for young women aged 15–17 and served on the management committees of several childcare centres. In 1999 she co-edited a book called 'Party Girls: Labor women now'. Penny has held a variety of positions in local branches and has been a delegate to state and national conferences.