The rise of ultra-processed foods (UPFs) in diets and associated harms to human and planetary health, has prompted calls for regulatory action. This challenges the approach of food regulatory systems that emphasize food safety risks over wider harms to population and ecological health and confronts the interests of a powerful UPF industry. To understand this challenge, our paper aims to understand the politics of UPF-related standard-setting in the Codex Alimentarius Commission (Codex), focusing on the development of new Front-of-pack Nutrition Labelling (FOPNL) guidelines. We adopted a case study design involving, i) collection of documents from the Codex Committee on Food Labelling (CCFL) meetings (2016-23), ii) identification, categorization, and enumeration of actors, and iii) guided by a constructivist framework, analysis of how actors framed and contested proposed food labelling provisions and characterized ‘risk/harm’. We found that country representation was skewed towards high-income, over middle-income, and low-income governments, and non-health ministries over health ministries. Delegations were also dominated by industry over civil society organizations, as were Codex observers. Contestations included preferential FOPNL schemes and which products would require FOPNL. Commercial and public health interest actors characterized ‘risk/harm’ as, non-scientific labelling that discourages consumer choice, and as, inadequate FOPNL leading to non-communicable diseases and trade challenges. Any ambition to comprehensively regulate UPFs requires examination of underlying interests and ‘risk/harm’ perceptions of actors, and how resource and power asymmetries can impact UPF-relevant standards. This calls into question the design of food regulatory systems, and especially how they impact human and planetary health.