To understand the impact of radiotherapy educational sessions with virtual reality on oncologic adult patients' psychological and cognitive outcomes related to the treatment experience. This review was performed according to the Preferred Reporting Items for Systematic Reviews guidelines. A systematic electronic search in three databases, MEDLINE, Scopus, and Web of Science, was conducted in December 2021 to find interventional studies with adult patients undergoing external radiotherapy who received an educational session with virtual reality before or during the treatment. The studies that provided qualitative or quantitative information about the impact of educational sessions on patients' psychological and cognitive dimensions related to RT experience were retained for analysis. Of the 25 records found, eight articles about seven studies were analysed that involved 376 patients with different oncological pathologies. Most studies evaluated knowledge and treatment-related anxiety, mainly through self-reported questionnaires. The analysis showed a significant improvement in patients' knowledge and comprehension of radiotherapy treatment. Anxiety levels also decreased with virtual reality educational sessions and throughout the treatment in almost all the studies, although with less homogeneous results. Virtual reality methods in standard educational sessions can enhance cancer patients' preparation for radiation therapy by increasing their understanding of treatment and reducing anxiety.