Background Oncological health care services are challenged by the increasing number of cancer survivors, long-term follow-up care, and fragmentation of care. Digital care platforms are potential tools to deliver affordable, patient-centered oncological care. Previous reviews evaluated only one feature of a digital care platform or did not evaluate the effect on enhancement of information, self-efficacy, continuity of care, or patient- and health care provider–reported experiences. Additionally, they have not focused on the barriers and facilitators for implementation of a digital care platform in oncological care. Objective The aim of this systematic review was to collect the best available evidence of the effect of a digital care platform on quality of care parameters such as enhancement of available information, self-efficacy, continuity of care, and patient- and health care provider–reported experiences. Additionally, barriers and facilitators for implementation of digital care platforms were analyzed. Methods The PubMed (Medline), Embase, CINAHL, and Cochrane Library databases were searched for the period from January 2000 to May 2020 for studies assessing the effect of a digital care platform on the predefined outcome parameters in oncological patients and studies describing barriers and facilitators for implementation. Synthesis of the results was performed qualitatively. Barriers and facilitators were categorized according to the framework of Grol and Wensing. The Mixed Methods Appraisal Tool was used for critical appraisal of the studies. Results Seventeen studies were included for final analysis, comprising 8 clinical studies on the effectiveness of the digital care platform and 13 studies describing barriers and facilitators. Usage of a digital care platform appeared to enhance the availability of information and self-efficacy. There were no data available on the effect of a digital care platform on the continuity of care. However, based on focus group interviews, digital care platforms could potentially improve continuity of care by optimizing the exchange of patient information across institutes. Patient-reported experiences such as satisfaction with the platform were considerably positive. Most barriers for implementation were identified at the professional level, such as the concern for increased workload and unattended release of medical information to patients. Most facilitators were found at the patient and innovation levels, such as improved patient-doctor communication and patient empowerment. There were few barriers and facilitators mentioned at the economic and political levels. Conclusions The use of digital care platforms is associated with better quality of care through enhancement of availability of information and increased self-efficacy for oncological patients. The numerous facilitators identified at the patient level illustrate that patients are positive toward a digital care platform. However, despite these favorable results, robust evidence concerning the effectiveness of digital care platforms, especially from high-quality studies, is still lacking. Future studies should therefore aim to further investigate the effectiveness of digital care platforms, and the barriers and facilitators to their implementation at the economic and political levels.