Cary Kennedy began her professional career as a budget analyst in Colorado Governor Romer's Office of State Planning and Budgeting. She then worked as a fiscal analyst for the Colorado Department of Health Care Policy and Financing. Kennedy left the department to lead a broad bi-partisan coalition to increase funding for Colorado's public schools. Amendment 23 was approved by Colorado voters in November 2000.

Kennedy worked for Educare Colorado to bring increased federal funding into Colorado to support early childhood education and later joined the Colorado Children's Campaign to support an initiative to expand health insurance coverage for low income children and fund cancer research. In 2004-2005, Kennedy served as the policy director for House Speaker Andrew Romanoff, and assisted in developing an historic budget compromise, Colorado's Referendum C, which was approved by Colorado voters in 2005.