Background: Twitter (now X) is a virtual social network commonly used by healthcare professionals. Little is known about whether it helps healthcare professionals to share, mobilise and co-create knowledge, or reduce the time between research knowledge being created and used in clinical practice (the evidence-to-practice gap). Musculoskeletal First Contact Physiotherapists (FCPs) are primary care specialists who diagnose and treat people with musculoskeletal conditions without needing to see their General Practitioner (family physician) first. They often work as a sole FCP in practice, hence are an ideal healthcare professional group with whom to explore knowledge mobilisation using Twitter.Objective: To explore if, how and why Twitter can be used to mobilise knowledge, including research findings, to inform FCP clinical practice.Methods: Semi-structured interviews of FCPs with experience of working in English primary care. FCPs were purposively sampled based on employment arrangements and Twitter use. Recruitment was via known FCP networks and Twitter, supplemented by snowball sampling. Online interviews used a topic guide exploring FCP's perceptions and experiences of accessing knowledge, via Twitter, for clinical practice. Data were analysed thematically and informed by the knowledge mobilisation mindlines model. Public contributors were involved throughout.Results: Nineteen FCPs consented to interview (Twitter users n=14, female n=9). Three themes were identified: 1) How Twitter meets the needs of FCPs, 2) Twitter and a journey of knowledge to support clinical practice and 3) Factors impeding knowledge sharing on Twitter. FCPs described needs relating to isolated working practice, time demands and role uncertainty. Twitter provided rapid access to succinct knowledge, opportunity to network and peer reassurance regarding clinical cases, evidence and policy. FCPs took a journey of knowledge exchange on Twitter, including scrolling for knowledge, filtering for credibility and adapting knowledge for in-service training and clinical practice. Participants engaged best with images and infographics. FCPs described misinformation, bias, echo chambers, unprofessionalism, hostility, privacy concerns and blurred personal boundaries as factors impeding knowledge sharing on Twitter. Consequently, many did not feel confident to actively participate with Twitter.Conclusions: This study explores if, how and why Twitter can be used to mobilise knowledge to inform FCP clinical practice. Twitter can meet knowledge needs of FCPs through rapid access to succinct knowledge, networking opportunities and professional reassurance. The journey of knowledge exchange from Twitter to clinical practice can be explained by considering the mindlines model, which describes how FCPs exchange knowledge in online and offline contexts. Findings demonstrate that