Exposure therapy (ET) forms a vital part of effective psychotherapy for anxiety-related presentations including anxiety disorders, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD), and is often underutilised in clinical practice. Using the Theoretical Domains Framework (TDF), this systematic review synthesised existing literature on the determinants of ET implementation for anxiety-related presentations and examined differences across presentations and developmental subgroups. Fifty-two eligible studies were assessed using the Mixed Methods Appraisal Tool, with 389 results (99%) mapped onto the TDF. Results suggested that clinicians' negative beliefs about the consequences of ET were commonly associated with reduced implementation. It also appeared that whilst broad unspecified ET training may be related to improved implementation for anxiety disorders; greater implementation for complex presentations (i.e., PTSD) likely requires more specialised training involving practical components. A subset of domains (e.g., social/professional role and identity) accounted for most results, whilst some remain unexplored (i.e., optimism; reinforcement; memory, attention, and decision processes) or underexplored (i.e., behavioural regulation). Likewise, specific presentations and developmental subgroups (i.e., PTSD and adults) represented a greater proportion of results in the literature than others (i.e., OCD and youth). Future research exploring ET implementation, across specific presentations and developmental subgroups, would benefit from integrating implementation science frameworks to guide the development of targeted, comprehensive strategies to close the research-practice gap of ET for the treatment of anxiety-related presentations.