As everyday practices are increasingly transferred to or mediated by digital technologies, spatial concepts such as ‘online social space’ are often used to characterize online interactions, colloquially and academically. However, it remains unclear whether and how digitally mediated interactions constitute social spaces. This chapter contributes to recent literature examining the spatiality of online social interactions using a phenomenological framework. Taking as a starting point the social-phenomenological insights found in the works of Alfred Schutz, the paper pursue three lines of argument. First, it shows how two recent applications of Schutz’s ideas to online social interactions fall short. Second, it argues that Schutz’s notion of immediacy and the emphasis on nearness in the phenomenological theories of place can be effectively applied to the question of online social spaces. Using this social-phenomenological framework, the paper shows how social media platforms constitute social spaces. Third, it argues that ideas in practice theory can shed further light on the spatiality of social media platforms, characterizing them as novel venues for older practices and thereby strengthening the social-phenomenological account. The chapter concludes by briefly noting two implications of viewing social media platforms as social spaces: first, for countering youth mental health issues related to social media use, and second, for making online public spaces more accessible.