In the digital age, traditional approaches to accessing information are disrupted by the ‘public’ nature of social media. The notion of accessing service users’ social media in social work practice is fraught with ethical issues around privacy and boundaries, yet lacks clear guidance from existing law and policy. This qualitative study sought to identify how mental health social workers were navigating these issues and how they thought practice could be developed. Ten mental health social workers, from one NHS Trust in England, were interviewed about their views and experiences around accessing service users’ social media without express permission. Semi-structured interviews were analysed using thematic analysis. Practitioners shared a variety of justifications for utilising social media, based upon statutory responsibility and professional values, but felt direct guidance/legislation and training would be helpful. A process of ‘digital reflexivity’ was outlined, which balanced reasons to access social media against considerations of privacy and the potential effects on the therapeutic relationship. Implications include the need for definitive guidance and training around if, when and how to access service users’ social media; inclusion of digital reflexivity in supervision and multidisciplinary meetings; educating service users about privacy controls; and a potential reconfiguration of theoretical boundaries to include the ‘public’ domain.