The purpose of this study is to explore the significant factors that drive consumers’ willingness to adopt a more plant-based diet, in both an Asian developing country (China) and a Western developed country (New Zealand), on the basis of three theories: meat attachment factors, the theory of planned behaviour and food choice motives. The data were collected through online surveys in China (n = 604) and New Zealand (n = 581). Confirmatory factor analysis and structural equation modelling were used for the data analysis. Consumers’ willingness to adopt a more plant-based diet was significantly linked to all the four meat attachment factors (Hedonism, Affinity, Entitlement and Dependence), four factors based on the Theory of Planned Behaviour (Subjective norms, Personal norms, Perceived behavioural control and Attitudes), and one food choice motive (Environmental concern). There were differences between China and New Zealand in the impact of the meat attachment factors and the theory of planned behaviour factors on the willingness to adopt a more plant-based diet.