PurposeThis study aims to identify the role of the voluntary simplicity lifestyle on the environmental activism behavioural trait, as well as the relationship of these two constructs on the sustainable fashion purchase intention.Design/methodology/approachA quantitative approach was taken with data collected through an online survey in Brazil, obtaining a valid sample of 364 respondents. The collected data were analysed through the structural equation modelling technique using SmartPLS-3.3.2.FindingsThe main findings of this study indicate that voluntary simplifiers exert a direct and positive influence on environmental activism. Also, consumers who embrace the values of voluntary simplicity and environmental activism are positively inclined to purchase sustainable fashion. In addition to sharing values converging to sustainability, consumers who have this profile can adopt sustainable fashion consumption as the mainstream of their purchasing decisions.Practical implicationsSimplifiers and activists represent a potential target audience to be observed by fashion companies that have focused on sustainability. Also, they can benefit from the findings in order to delineate the type of product to be offered as well as assist in the development of communication strategies.Originality/valueThis study is innovative by bringing constructs that are emerging in the field of consumption behaviour and sustainability. In addition, it contributes, at the same time, to advance research on the behavioural profile of individuals in favour of sustainability, by pointing out to voluntary simplicity and environmental activism as important antecedents of sustainable fashion consumption behaviour.