Cook coached and taught volleyball in Huntington Beach, and served as Parent Teacher Association president for Vista View School in Fountain Valley. In 1978 Debbie and John purchased a small office-equipment business which they ran for 14 years. During those years Cook obtained a patent for the business’s shelving system. As a political novice in 1990, Cook was the main force behind the Huntington Beach city voter initiative Measure C, a pro-environment City Charter amendment that forbids sale or lease of park or beach land without a citywide vote. Despite opposition by the city council majority being against the initiative, voters approved it. In December 1994, Cook was admitted to the California bar. Cook served as attorney for the Bolsa Chica Land Trust, and took part in the efforts to preserve the Bolsa Chica Wetlands from development. In 2000, Cook became a member of the city council for Huntington Beach, California. In 2001 Cook became the mayor of Huntington Beach, California. Cook was reelected in 2004. The office of the Mayor of Huntington Beach is a rotating position within the city council. She also has served as President of the Orange County Division of the League of California Cities, Chair of the League of California Cities Administrative Policy Committee and Chair of the Orange County Parks Commission. She helped lead the fight to prevent the Orange County Sanitation District from massive dumping of partially treated wastewater into the ocean. In 2007, Huntington Beach joined the U.S. Mayor’s Agreement on Global Warming.cl
2008 campaign for Congress
On February 2, 2008 Debbie Cook announced her Democratic candidacy for California's 46th congressional district against incumbent Republican Dana Rohrabacher. Cook defeated Huntington Beach business owner Dan Kalmick in the June 3, 2008 primary for the Democratic nomination. The Treasurer of the California Republican Party filed suit against Cook and the Orange County Registrar regarding Cook's ballot designation. The suit has been seen as frivolous and politically motivated. It was dismissed by the California Court of Appeals. According to FEC reports, Cook outraised Rohrabacher in the first and second quarters of 2008, although Rohrabacher in total had raised $323,966 compared to Cook's $157,269 by the end of the second quarter 2008. In the end, Cook failed to oust the incumbent, winning only 42.4% of the vote to Rohrabacher's 53.2%.
Personal life
On 1975, Cook married John Fisher. They have one son. In 1986, Cook and her family moved to Huntington Beach, California.