The modern food system is characterised by 1) unsustainable agricultural practices, heavily dependent on agrochemical inputs and leaking large amounts of reactive nitrogen (N) whilst degrading soils, and 2) the consumption of energy-rich but nutrient-poor foods, contributing to non-communicable diseases related to malnutrition. Substituting cereals with low-input, protein- and fibre-rich legumes in the production of mainstream foods offers a promising solution to both issues. Chickpea (Cicer arietinum) is a leguminous crop that can be grown with little or no synthetic N fertiliser. We performed life cycle assessment (LCA) to compare the environmental footprint of pasta made from chickpeas with conventional pasta made from durum wheat (Triticum durum) from cradle to fork. Two functional units were used, an 80g serving of pasta, and a Nutrient Density Unit (NDU). Environmental burdens per serving were smaller for chickpea pasta across at least 10 of the 16 impact categories evaluated. Global warming, resource use minerals and metals, freshwater eutrophication, marine eutrophication, and terrestrial eutrophication burdens were smaller than those of durum wheat pasta by up to 45%, 55%, 50%, 86%, and 76%, respectively. Cooked chickpea pasta contains 1.5 more protein, 3.2 times more fibre and 8 times more essential fatty acids than cooked durum wheat pasta per kcal energy content. Thus, the environmental advantage of chickpea pasta extended to 15 of the 16 impact categories when footprints were compared per unit of nutrition. Global warming, resource use and eutrophication burdens per NDU were 79–95% smaller for chickpea pasta than for durum wheat pasta. The one major trade-off was land use, where chickpea pasta had a burden 200% higher per serving, or 17% higher per NDU, than wheat pasta. We conclude that there is high potential to simultaneously improve the environmental sustainability and nutritional quality of food chains through simple substitution of cereals with legumes in staple foods such as pasta. Breeding and agronomic management improvements for legumes could reduce the yield gap with cereals, mitigating the land use penalty. Meanwhile, the higher protein content of chickpea pasta could contribute towards wider environmental benefits via animal protein substitution in diets, and merits further investigation. Consumers who look for the traditional taste and texture of wheat pasta can achieve these aspects by cooking the chickpea pasta al dente and combining it with a typical pasta sauce, which will hide its subtle nutty taste.