This paper explores the dynamic role of WhatsApp in political communication among Spanish users, with a particular focus on the platform’s impact on affective polarisation as one of today’s epitomes of emotional expression. Using a combination of quantitative data from a nationally representative survey and qualitative insights from focus group discussions, the study investigates how we use WhatsApp to discuss public affairs, how the interaction between affordances and the group dynamics of close social ties affects that discussion, and how this may relate to affective polarisation. The findings highlight that WhatsApp is a significant medium for political talk, especially among younger and more educated users. Additionally, the research underscores the importance of understanding the unique affordances of WhatsApp, such as its privacy and immediacy, which create a hybrid space for public-interpersonal communication. These features differentiate WhatsApp from other social media like Twitter and Facebook and are key to grasp the link between WhatsApp usage(s) and affective polarising outcomes, even though this association is strongly moderated by other variables, such as political interest or perceived party system polarisation.