The overturning of Roe v. Wade and the repeal of Germany’s abortion advertisement ban in June 2022 represent a momentous shift in the global landscape of reproductive rights, amplifying contentious debates around bodily autonomy and women’s rights. Feminist activism, traditionally rooted in body politics, has adapted to digital platforms, utilising their affordances to mobilise around socio-political issues such as abortion rights. This paper investigates the affective dynamics, i.e., intensities and registers, of feminist digital activism through the lens of affect theory and feminist media studies, with a focus on the #mybodymychoice TikTok challenge. We examine how TikTok’s algorithmically driven, viral structure shapes the affective intensity of the challenge; and introduce the concept of affective registers to analyse how the platform’s multimodal affordances foster distinct types of memetic performances that privilege certain forms of feminist digital activism. Our findings reveal how affective registers of joy, anger, shock, and solidarity circulate within the challenge, fuelling wide, intense, but ephemeral mobilisation while also exposing the risks of political dilution. Through our typology of affective registers, we examine the tension between popular feminist performances of “happy feminism”—where joy and personal empowerment prevail—and more confrontational forms of “killjoy feminist activism,” shedding light on the potential and limitations of feminist activism on TikTok and the platform’s ability to foster affective solidarity while also commodifying affect and constraining sustained political impact. Thus, this study exemplarily delineates the broader dynamics and contours of contemporary feminist digital activism, illustrating how playful, intimate, and vivid memetic performances both amplify and reshape feminist activism in digitally networked societies.