Cook has a rich background in public service and has been a dedicated member of the Australian Labor Party (ALP) for many years. His ascent to the premiership is marked by a steadfast commitment to health, economic development, and social justice.

Cook's educational background is rooted in the humanities and management, holding a Bachelor of Arts in Public Administration from Murdoch University and a Master of Business Administration from Curtin University. In 1986, while at Murdoch, Cook was elected as a student member of Senate. Six months into his tenure he resigned from the position in order to move to Melbourne and take up his new appointment as President of the National Union of Students.  

Image caption: Roger Cook, Murdoch University student elections (May 1984)

After graduating, Cook worked in the offices of a number of Labor MPs, including Stephen Smith, Jim McGinty, and Chris Evans. He served as state president of the Labor Party from 1999 to 2000. Cook later became involved with Aboriginal advocacy groups, serving at various times as a policy coordinator for the Western Australian Aboriginal Native Title Working Group, as CEO of the Yamatji Marlpa Barna Baba Maaja Aboriginal Corporation, and as government relations manager for the South West Aboriginal Land and Sea Council. From 2004 to 2008, he was state manager of CPR, a public relations firm which is closely associated with the Labor Party. 

Cook entered the political arena in 2008, when he was elected as the Member for Kwinana in the WA Legislative Assembly. Within weeks he was appointed Deputy Leader of the Opposition, a role he held until 2017. 

In 2017, the Labor Party won a landslide victory, and Cook was appointed Deputy Premier and Minister for Health and Mental Health in Premier Mark McGowan's cabinet. His tenure as Health Minister was characterised by substantial reforms and improvements in the healthcare system. Cook was instrumental in the implementation of the ‘Sustainable Health Review’, which aimed to create a more efficient and sustainable healthcare system in WA. His leadership was also pivotal during the COVID-19 pandemic, where his proactive measures and clear communication were widely praised for keeping WA relatively safe and minimising the impact of the virus. He also played a key role in the passage of voluntary assisted dying legislation in 2019.