Various fiscal policies have been proposed to incentivise healthy and sustainable diets, with differing attributes and levels. Public support can influence the ability for such policies to be implemented but is currently poorly understood, so two discrete choice experiments (DCEs) were used to measure such preferences among 2020 adults in the UK. The attributes and levels for 192 policy options were identified using a scoping review that comprehensively documented existing or proposed food-based fiscal policies. For health-related taxes and subsidies, options that prioritised protecting the NHS budget were most preferred for all respondents, which held across variation in 9 respondent characteristics. For sustainability taxes, avoiding donating to other countries was a clear priority for all respondents, and again held across 9 respondent characteristics. These results could help to shape UK policy while these methods could be used to understand policy preferences elsewhere.