Purpose The aim of the study was to investigate the experiences of people with traumatic brain injury (TBI) and rehabilitation professionals in use of social media after TBI. Design Metasynthesis of a multilevel mixed-methods research design was used in the study. Method A qualitative metasynthesis of (a) evidence in the literature regarding the use of communication technologies and social media after TBI, (b) Twitter data and network analysis, (c) interviews with people with TBI (n = 13), (d) focus groups with TBI rehabilitation professionals (n = 11), and (e) a review of current guidance on safe use of social media was conducted. Results People with TBI adopt a trial-and-error approach to using social media. Their meaningful use and a sense of connection enable them to develop social media mastery. TBI rehabilitation professionals' concerns regarding potential risks associated with using social media might lead them to restrict social media use during rehabilitation. Conclusions Access to proactive training in social media use and a supportive network of rehabilitation professionals, family, and friends can enable people with TBI to develop social media mastery through working collaboratively on social media goals. This metasynthesis of research culminates in an evidence-based protocol for assessing and supporting a person with TBI's social media goals to guide clinical practice and future research in the field.