Global greenhouse gas emissions associated with peat soils under horticultural production may be substantial, and contribute towards degradation of a key global carbon stock. Emissions from horticultural peat soils are currently poorly quantified, restricting the scope for prioritising sectorial mitigation efforts. This study provides the first UK estimate of emissions of CO2, N2O and CH4from peat soils under horticultural production, and focuses the evidence base for mitigation efforts, using multiple, complementary methods. Emissions quantification was addressed in a field study over a complete annual cropping cycle, and using a mathematical modelling approach. Identification and prioritisation of mitigation measures was achieved through a search of the scientific literature, followed by short-listing of measures using a Best-Worst Scaling survey approach, and field-testing of a selected small number of candidate measures in a mesocosm experiment. This study indicated that IPCC emissions estimates may represent an underestimateof peatland N2O emissions, and that net emissions of CO2and CH4represent a substantial annual soil carbon loss. Calibrated emissions models providea means of upscaling estimates, but the DNDC (Denitrification-Decomposition) model offers limited potential at the present time. A holistic approach to mitigation is recommended, encompassing retailers and consumers as well as farmers, in an effort to reduce food waste at all stagesof the food chain. On-farm mitigation should focus in the short-term on nutrient management, and in the longer term, on considering alternative land uses.