Background Coeliac disease (CD) is a chronic, autoimmune disease that prevents individuals from processing gluten, leading to adverse health effects. People with CD should adhere to a gluten‐free diet (GFD); however, adherence rates are well below optimal in adults with CD, ranging between 42% and 91%. To date, limited evidence is available on the nature and magnitude of factors that affect adherence to GFD. The present study aimed to develop a systematic review that critically appraises and synthesises evidence on facilitators and barriers that affect adherence to GFD among adults with CD. Methods Four databases were searched (Ovid Medline, CINAHL, PsychInfo and Embase) using variant keywords to identify empirical studies meeting the inclusion/exclusion criteria. A coding scheme was developed to extract relevant information from each article. Results Forty articles were included. Grounded in the bioecological theory of development, we synthesised the facilitators and barriers in the literature into a social ecological model with multiple levels: system, community, organisational, interpersonal and individual. The studies varied by design and level of evidence; only one randomised trial was identified. The most significant facilitators include (% of studies): increased education (22.5%); increased knowledge of a GFD (20%); increased intention/self‐regulatory efficacy (17.5%); and coeliac association membership (12.5%). The most significant barriers include: lower knowledge of CD (35%); restaurant/supermarket shopping (30%); poor patient education from practitioner (17.5%); and low intention/motivation to adhere to a GFD (17.5%). Conclusions Improving knowledge of a GFD, becoming a member of a coeliac association, and improving practitioners’ abilities to educate patients on CD will create opportunities for improved adherence to GFD among adults with CD.