There is widespread recognition that a transformation of food systems is needed to improve environmental sustainability. As part of efforts to hold food companies accountable for their role in improving the environmental sustainability of food systems, there is a critical role for monitoring and benchmarking of company actions. This study aimed to develop a proposed set of metrics for assessing the commitments and practices of food companies regarding environmental sustainability. Guided by an inventory of existing sustainability reporting frameworks and benchmarking initiatives, we proposed 37 indicators for assessment, categorised into ten domains, covering strategy, packaging, greenhouse gas emissions, energy use, water, biodiversity, food waste, compliance and reducing animal-sourced foods. We refined the indicators after consultation with academic experts. We discussed implementation feasibility with sustainability managers from three major food companies in New Zealand. Feedback highlighted the need to pilot test methods for applying the indicators in practice, including assessment of a company’s impact across the supply chain, refining indicator scoring criteria, and weighting indicators based on company- and sector-specific priority areas of focus. Assessment of food companies using the proposed set of metrics can improve accountability for action and inform government regulatory responses.