Background This study in Portugal aims to monitor the Corporate Political Activity (CPA) in the food industry. Portugal provides a compelling case study due to its robust implementation of public health policies. Methods A systematic qualitative approach proposed by Mialon et al., a part of the INFORMAS Module 3, was employed. This method is based on the analysis of publicly available information. Key industry actors were selected through expert consultation and market analysis using EuroMonitor data. Information sources included industry, government, and academic materials accessed via websites and news. A thematic qualitative analysis was conducted involving iterative steps: identifying CPA practices based on predefined strategies - Taxonomy of Action Strategies: access and influence policymaking, use the law to obstruct policies, manufacture public support, shape evidence, displace and usurp public health, and manage reputations -, recording methods in a database, and saving evidence. Data collection spanned October 2023 to April 2024, covering materials from 2022 to 2023. Results Twenty-five key players were identified, including processed food and non-alcoholic beverage manufacturers, fast food companies, food retailers, and national trade associations. Food retailers, notably Jerónimo Martins, Lidl, Mercadona, and Sonae, showcased a higher prevalence of CPA. Nestlé and Sumol+Compal also emerged as prominent actors. The food industry in Portugal employs diverse strategies and tactics primarily focused on shaping evidence and managing reputations. While instances of displacing public health priorities and manufacturing public support were observed, they were relatively fewer. Only APED and FIPA showed engagement in policymaking influence. Conclusions Vigilant monitoring of CPA in the food industry in Portugal reveals dominant tactics of shaping evidence and managing reputations. Understanding these strategies is vital for policymaking to safeguard public health. Key messages • The food industry in Portugal employs diverse strategies, primarily shaping evidence and managing reputations, to influence public health policies. • Monitoring the Corporate Political Activity is key to preserving the integrity of public health policymaking in Portugal’s food industry.