Objective: This cross-sectional study aimed to understand the actual situation of shared decision-making (SDM) and identify the challenges of implementing SDM among Japanese gynecologic cancer patients and healthcare professionals (HCPs). Methods: Adult Japanese women undergoing chemotherapy for endometrial or ovarian/ fallopian tube cancer and HCPs who prescribed/administered treatment were enrolled. Data were collected via a web-based questionnaire. Primary endpoints were the actual and desired status of SDM for patients by preferred role (active, collaborative, passive), and important aspects in drug selection for patients and HCPs. SDM treatment preferences were determined using the Control Preferences Scale. Results: Respondents comprised 154 patients (77 for endometrial and 77 for ovarian/fallopian tube cancer), 153 physicians, 166 nurses, and 154 pharmacists. Among patients, 53.9% desired an active role in decision-making, and 55.8% participated; 25.3% desired a collaborative role, and 14.3% participated; and 20.8% desired a passive role, and 29.9% participated.Most patients with a collaborative role in decision-making (86.4%) were “very satisfied” or “somewhat satisfied” with their communication with physicians, compared with 60.4% and 73.9% of respondents with active and passive roles in decision-making, respectively. In daily practice, 23.5%, 47.6%, and 19.5% of physicians, nurses, and pharmacists, respectively, confirmed “awareness” of SDM. Regarding treatment expectations, patients ranked “complete elimination of cancer,” and HCPs ranked “live longer” as the most important. Conclusion Most patients desire involvement in their treatment decisions. Additionally, treatment expectations differ between patients and HCPs. Increasing SDM awareness, implementing it systematically, and addressing patients’ needs for collaborative roles in decision-making is essential.