Background: There is increasing recognition of the importance of undertaking process evaluations alongside implementation of health interventions by examining mechanisms of impact and contextual factors. However, a comprehensive synthesis of process evaluations undertaken alongside clinical trials in hospital settings is lacking. We undertook a scoping review to address this gap. Methods: This review was guided by the methodological framework for scoping studies. Studies were identified using four databases; Ovid Medline, EBSCO CINAHL, EMBASE and Scopus. Two authors independently screened all titles and available abstracts, with a third author available to adjudicate. Studies were eligible for inclusion if they described a process evaluation undertaken alongside a randomised controlled trial in the hospital setting. Data were abstracted by one author and checked by two others and analysed both descriptively and using inductive content analysis. Results: Data were extracted from 30 articles reporting on 15 trials, most of which were cluster randomised trials (c-RTs) (n = 12). The most common data collection methods used in process evaluations were interviews, questionnaires or surveys, and records or logs. Data analysis revealed three themes relative to how authors: use process data to interpret, understand and explain trial outcomes; evaluate responses to the intervention; and consider the implementation context. Conclusions: Findings from this review demonstrate the complex nature of intervention implementation in the hospital setting. Overall, there is need for standardised reporting of process evaluations and more explicit descriptions of how authors use frameworks to guide their evaluation.