Abstract Loneliness is recognised as a ‘grand challenge’ for social work, given its negative impact on health and well-being. But there has been limited progress on how social workers should respond. We aimed to characterise social work research on loneliness from 2016 to 2021, to inform policy, practice and training. We utilised the Joanna Briggs Institute methodology for scoping reviews with a narrative synthesis of results. Data were extracted on study characteristics, assessment and intervention strategies, the role of social workers in this literature and limitations in the research. The final review consisted of 366 studies. Results showed a steady growth in research outputs on loneliness over time, predominantly (40 per cent) aimed at improving social work practice. Qualitative research methods (45 per cent) and cross-sectional study designs (61 per cent) were most common. Fewer than one-third of studies (32 per cent) used a formal assessment tool to identify loneliness. The most common intervention strategies examined were enhancing social relationships (30 per cent) and person-centred solutions (21 per cent). A slight majority (57 per cent) of peer-reviewed journal articles had a social work lead author. The review indicates social workers are engaged in research and action on loneliness, but ensuring this expertise is visible, led by social workers and accessible, remains a challenge.