Cook was born in Perth, and attended Scotch College. He went on to Murdoch University, completing a Bachelor of Arts degreein public administration, and later completed a graduate business diploma and also a Masters of Business Administration at Curtin University. Whilst at Murdoch, Cook became involved in student politics, serving as a student representative on the university's senate. He was also involved in the establishment of the National Union of Students in mid-1986, becoming its first national president as a representative of the National Organisation of Labor Students. 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.
Politics
At the 2008 state election, Cook won the seat of Kwinana in a tightly fought contest, winning by 300 votes from independent candidate Carol Adams, the mayor of the City of Kwinana. Adams had unsuccessfully attempted to gain Labor pre-selection, and later accused Alan Carpenter of "parachuting" Cook into the seat. On 16 September, ten days after the election, Cook was elected to the position of deputy leader of the Labor Party under Eric Ripper. He is a member of the Labor Left faction, backed by the United Voice trade union. After Ripper was replaced by Mark McGowan as leader of the opposition in January 2012, Cook maintained his position as deputy leader. He was re-elected at the 2013 state election in a rematch with Adams, winning an increased majority. However, Kwinana was a very safe Labor seat in a "traditional" two-party matchup with the Liberals; Cook would have won it in both 2008 and 2013 with majorities of well over 10 percent in a traditional contest with a Liberal candidate. Proving this, Cook was easily reelected in 2017 amid the massive Labor wave that swept through Perth, taking over 68 percent of the two-party vote, a "traditional" two-party swing of seven percent.
Portfolios
Cook has held the following portfolios since his election in 2008: