Background <p>Despite the availability of effective interventions for cancer prevention, Japan faces substantial evidence–practice gaps, such as in the low utilization of smoking cessation treatments, HPV vaccination, and cancer screening. Implementation research plays a critical role in bridging this gap by promoting the uptake of effective interventions in real-world settings. Globally, however, prioritization of the implementation of these various interventions remains unclear. To address this need, we conducted a structured priority-setting exercise using the CHNRI method and incorporating perspectives from diverse stakeholders, including citizens.</p> Methods <p>We conducted a four-phase research prioritization process using the CHNRI method to identify which effective interventions for cancer prevention should be prioritized for implementation in Japan. The process included listing effective interventions for cancer prevention, surveying stakeholders, conducting a web-based survey among researchers, and calculating priority scores.</p> Results <p>Among 215 invited researchers, 92 (42.8%) and 67 (31.2%) researchers responded to the first and second surveys, respectively. In both surveys, physicians accounted for the largest proportion of respondents. Across both surveys, HPV vaccination for females, cervical cancer screening, fecal occult blood testing (FOBT), mammography, and tobacco control policies were identified as top priorities.</p> Conclusions <p>Priorities for implementing effective interventions for cancer prevention were set through collaboration with researchers and citizens, providing a foundation for future research and progress.</p>