In the light of climate change and ever-increasing evidence of the need for urgently changing food production and consumption, how do brands enter and leverage this debate? How can brands become activists by mobilizing debates around a political cause, and how can those debates promote the legitimacy of emerging industry practices? Through a case study of the now-famous food and beverage brand Oatly, this paper describes how brand-induced political activism can challenge consumption, production, policy, and ideologies. It can promote brand development and positioning, provided that the brand has earned legitimacy. This study suggests that the new branding principle in the age of the climate crisis and eco-anxiety can be characterized as ‘citizen activist,’ in which consumer culture goes beyond the cultivation of self, focusing instead on systemic changes in production and consumption.