BackgroundComplexity theory has been chosen by many authors as a suitable lens through which to examine health and social care. Despite its potential value, many empirical investigations apply the theory in a tokenistic manner without engaging with its underlying concepts and underpinnings.ObjectivesThe aim of this scoping review is to synthesise the literature on empirical studies that have centred on the application of complexity theory to understand health and social care provision.MethodsThis scoping review considered primary research using complexity theory-informed approaches, published in English between 2012 and 2021. Cochrane Database of Systematic Reviews, MEDLINE, CINAHL, EMBASE, Web of Science, PSYCHINFO, the NHS Economic Evaluation Database, and the Health Economic Evaluations Database were searched. In addition, a manual search of the reference lists of relevant articles was conducted. Data extraction was conducted using Covidence software and a data extraction form was created to produce a descriptive summary of the results, addressing the objectives and research question. The review used the revised Arksey and O’Malley framework and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis Extension for Scoping Reviews (PRISMA-ScR).Results2021 studies were initially identified with a total of 61 articles included for extraction. Complexity theory in health and social care research is poorly defined and described and was most commonly applied as a theoretical and analytical framework. The full breadth of the health and social care continuum was not represented in the identified articles, with the majority being healthcare focused.DiscussionComplexity theory is being increasingly embraced in health and care research. The heterogeneity of the literature regarding the application of complexity theory made synthesis challenging. However, this scoping review has synthesised the most recent evidence and contributes to translational systems research by providing guidance for future studies.ConclusionThe study of complex health and care systems necessitates methods of interpreting dynamic prcesses which requires qualitative and longitudinal studies with abductive reasoning. The authors provide guidance on conducting complexity-informed primary research that seeks to promote rigor and transparency in the area.RegistrationThe scoping review protocol was registered at Open Science Framework, and the review protocol was published at BMJ Open (https://bit.ly/3Ex1Inu).