How to enable more widespread sustainable food choice and diets is an unresolved challenge. A consumer-friendly sustainability labelling scheme ‘holistically’ encompassing all sustainability aspects ‘in one’ might be a way forward, but this idea entails both opportunities and challenges, not least given that this requires a common understanding of what sustainability is, and which sustainability dimensions need to be communicated. We address this global problem through qualitative expert elicitation, interviewing sustainability and labelling experts from academia, think tanks and non-governmental organisations, food producers, the retail sector, and governmental bodies about the steps to consider and the challenges and opportunities entailed. Our findings reveal mixed arguments for and against a holistic sustainability label. Experts suggest that consumers and food sector stakeholders appear to be ‘ready’ for and perceive such a label as a desirable tool. Nevertheless, unanticipated consequences could potentially hamper its impact, and challenges are the complexity of the issue, the lack of data, and that it is unlikely sector stakeholders can agree. We conclude that the most important aspects to improve effectiveness are the information content allowing to compare to alternatives, a consistent application on all products through mandatory labelling, and coupling implementation of a label within a broader supportive policy mix. We discuss four different policy scenarios that each show how the opportunities and challenges can play out in different potential routes from here.