The current diet with high proportions of animal products contributes significantly to harmful greenhouse gas emissions and ultimately to climate change. A more plant-based diet could counteract this. Thus, a large range of plant-based alternatives to milk and dairy are being developed, and the consumption of these products is increasing. Here, we characterised consumers and non-consumers of plant-based alternatives to milk, yoghurt, and cream, and investigated reasons for and against consumption of these products. We also studied consumers’ attitudes towards food shopping behaviour, health aspects, veganism, and sustainability using an online survey administered to 1,204 participants in German- and French-speaking parts of Switzerland. Participants consuming these plant-based products less than 2–3 times per year were assigned to the non-user group (n = 610). Those consuming these products at least 2–3 times per year were assigned to the user group (n = 594). We found that users tended to be young, well-educated urban flexitarians. The most frequently consumed plant-based alternatives were soy, almond, and oat drinks. The most prominent reasons for consumption of these products were taste, health (including allergies and intolerances), and environmental sustainability. Users and non-users of plant-based alternatives differed significantly in their attitudes and beliefs regarding the positive climate impact of a vegan diet (users agreed, non-users disagreed), which can be seen as an indication for cognitive dissonance. These observations have important implications for research and practice, offering a better understanding of the growing group of consumers who use plant-based alternatives for a more sustainable diet.