Introduction: Ecological momentary assessment (EMA) is an emerging method to assess an individual's current thoughts, affect, behaviour, physical states and contextual factors as they occur in real-time and in their natural environment. Whereas EMA is frequently used in mental health, little is known about the added value of EMA in oncology research. This review aimed to synthesise methodological information and results of studies that applied EMA among patients with cancer to inform future researchers about the opportunities and challenges. Methods: We included full-text articles on studies that: (a) were conducted among adult cancer patients; and (b) examined cancer and treatment-related experiences by EMA. Information from selected studies was synthesised: study designs, EMA data collection methods, response-related results and main findings. Results: Twelve studies were included, which all applied an observational design. The EMA data collection methods varied considerably and the reporting of response-related results were poor. Nevertheless, EMA was found feasible as no systematic patterns of problems were reported and reported response-related results were acceptable. Furthermore, EMA was found useful as it facilitated examination of real-time experiences and behaviour. Conclusion: Ecological momentary assessment is useful and feasible in oncology research. Future studies would benefit from guidelines for designing and reporting EMA studies.