OBJECTIVES: There is limited research focused explicitly on understanding how commercial actors use different forms of power to influence policy decision making in Thailand. This study aimed to identify how the food industry has used structural, instrumental and discursive power to influence policy on restricting food marketing in Thailand. STUDY DESIGN: Qualitative study using in-depth semistructured interviews SETTINGS: Thailand. PARTICIPANTS: The interviews were conducted with 20 participants (of a total of 29 invited actors) from government, civil society, technical experts, international organisation and the food and advertising industry. Interview data were identified in the transcripts and analysed using abductive methods. RESULTS: Non-commercial actors perceived the commercial actors' structural power (its economic influence and structurally privileged position) as central to understanding the government having not implemented policy to restrict food marketing. The commercial actors' instrumental power was observed through sponsorship, campaign and lobbying activities. Discursive power was used by the industry to shift responsibility away from the food companies and onto their customers, by focusing their messaging on freedom of consumer choice and consumer health literacy. CONCLUSIONS: This study examined different types of power that commercial actors were perceived to use to influence policy to restrict food marketing in Thailand. The study showed arguments and institutional processes used to enhance commercial actors' ability to shape the policy decision for nutrition, public opinion and the broader regulatory environment. The findings help governments and other stakeholders to anticipate industry efforts to counter policy. The findings also suggest the need for governance structures that counter industry power, including comprehensive monitoring and enforcement in policy implementation.