Grass-derived proteins, as a novel and sustainable source of nutrition, offer potential solutions for food security and environmental sustainability but face challenges in consumer adoption. This study investigates the factors influencing consumer acceptance and intentions to consume grass-derived proteins in the United Kingdom using a Structural Equation Modelling (SEM) approach to capture the complex relationships among psychological, social, and product-related variables. Data were collected via a cross-sectional survey of 990 participants, capturing attitudes, subjective norms, perceived behavioural control, facilitators and food neophobia. The findings reveal that facilitators such as perceived health benefits, nutritional value, and safety significantly enhance consumer willingness to adopt grass-derived ingredients. Further, negative attitudes reduce positive attitudes towards meat preferences which in turn leads to positive intentions to consume grass-derived proteins. A multigroup analysis of the meat avoiders-reducers and regular meat consumers reveals different pathways influencing their behavioural intentions. Facilitators emerge as the strongest predictors of intention for both groups, but differences in the strength of pathways underscore the need for tailored marketing and policy interventions. For avoiders-reducers, direct pathways from facilitators to intention dominate, while indirect pathways involving attitudes towards meat hold minimal influence. Conversely, meat consumers exhibit stronger resistance tied to cultural perceptions of grass-derived products. These findings suggest emphasizing strategies to enhance consumer familiarity and address sensory concerns while leveraging the environmental and health benefits of grass-derived proteins. By addressing group-specific drivers and barriers, these efforts can foster broader acceptance of sustainable food innovations, contributing to global goals for food security and environmental sustainability.