This paper draws on a digital ethnography with young activists in Western Kenya to explore how WhatsApp’s affordances mediate citizenship. It applies an intersectional lens to highlight sites of oppression and invisibility. The paper makes two central arguments. Firstly, it finds that WhatsApp is not only important for participants because of its communicative and organisational affordances, but also for agentic and social affordances that relate to activists’ sense of belonging and purpose, and the discursive affordances that enable the building of narratives, making it a space for constructing and rehearsing citizenship. Secondly, it finds that inequalities in meaningful online access hindered some participants from these spaces of belonging, interaction, and visibility. These inequalities intersect and risk amplifying existing sites of disadvantage, like those related to gender, class or location. An intersectional digital rights approach is needed in the design of communication strategies by activists or organisations in civic engagement processes.