This study identifies materialism and well-being as the determinants of buycott behaviour. A buycott is a form of prosocial behaviour that supports the targets through purchasing behaviour, contrary to boycotts, and is a new form of value creation in society. Value creation in marketing goes beyond prices and profitability but includes doing social good and improving well-being as a co-creation phenomenon with customers. A buycott is also more than just consumption behaviour; it is the behaviour of consumers who support and aid companies and is a co-creation of new social value. Although it is expected to be related to materialism because it involves consumption behaviour, the relationship has not yet been discussed. This study examines the possibility that materialism, altruism and well-being promote not only charity behaviour intentions but also buycotts and boycotts. By using Structural Equation Modelling based on Japanese data, where buycott studies have not been widely conducted, this article generalizes previous studies and clarifies the relationship between materialism and prosocial behaviour. The findings reveal that while materialism promotes charity, buycotts and boycotts, it does not necessarily affect buycotts via well-being. This indicates the relationship between materialism and buycotts and demonstrates the differences between buycotts and charity as prosocial behaviour.