Hate speech against environmental activists has been on the rise globally, alongside a forceful criminalization of the climate movement in Western Europe. This article analyses anti-environmentalist speech and actions against Extinction Rebellion (XR) Finland, an environmental movement that employs non-violent direct action and civil disobedience to persuade individuals and institutions to address the ongoing ecological emergency. The materials consist of online commenting evoked by the news coverage of XR Finland’s protests in October 2022 and May 2023, and ethnographic data from the protest sites. The data ranges from scorn and stigmatizing insults to fantasies of violence and physical assaults at the demonstration sites. The article discusses this data through the concept of toxic speech and explores the different sensibilities of such speech: (1) the ironic and dismissive sensibility, (2) the emotionally invested sensibility and (3) the punitive, resentful sensibility. This article highlights how these sensibilities and related affective practices are embedded in and compounded by gendered, class-based, ageist and ableist systems of power and argues that anti-environmentalist toxic speech contributes to environmental activism’s delegitimization and stigmatization. It suggests that toxic speech normalizes violence towards activists and can ultimately violate activists’ civil and political rights.