When do corporate climate commitments translate into substantive emissions reductions rather than remaining symbolic? This study draws on a multilevel political economy framework: corporate climate action depends on both bottom-up managerial agency and top-down regulatory signals. Using panel data on large U.S. publicly traded firms, the study examines how managerial agency and organizational capabilities—reflected in dedicated leadership, environmental commitments, and innovation capacity—interact with external policy pressures. A quasi-experimental design compares firms facing differing regulatory pressure across hard-to-abate and consumer-oriented sectors, isolating the separate and joint roles of policy threats and managerial agency. Stronger policy signals increase firm participation in climate disclosure programs across sectors, but reduce emissions intensity only when firms possess managerial capabilities. This decarbonization channel is strongest in hard-to-abate sectors where regulatory pressure is most direct, whereas consumer-oriented sectors exhibit less substantive, more symbolic responses. These findings show that managerial agency and organizational capabilities do not operate in a vacuum, but are activated and reinforced by external policy signals. By identifying the conditions under which private actors convert internal and external institutional pressures into real decarbonization, this study offers large-scale empirical evidence on when multilevel governance—spanning regulatory, voluntary, and organizational mechanisms—effectively drives corporate climate action.