OBJECTIVE Participatory workplace environmental improvement programs have proven to be effective in addressing mental health issues in the workplace. However, their implementation remains challenging. This study aimed to identify the facilitators and barriers faced by part-time occupational health physicians in proposing and implementing such programs and to develop effective implementation strategies. METHODS A web-based questionnaire survey was conducted among part-time occupational health physicians between September and October 2023. This survey examined their experiences in proposing workplace environment improvements, their knowledge of participatory workplace environmental improvement programs, and their experience in proposing and introducing such programs. It also assessed the facilitators and barriers to the introduction and implementation of such programs. Respondents who had proposed such a program to their client companies were asked to connect the research team with the individual responsible for workplace environmental improvement at those companies. After obtaining consent, we interviewed these individuals in November and December 2023 to explore the facilitators and barriers to introducing participatory workplace environmental improvement programs. The questionnaire and interview data were analyzed using the occupational health version of the Consolidated Framework for Implementation Research (CFIR), and implementation strategies were developed with reference to expert recommendations for implementing change (ERIC). RESULTS We received 57 responses overall. Of the 49 respondents who were familiar with participatory workplace environmental improvement programs, 33 (67.8%) had proposed them. Of those with the proposed experience, 11 (33.3%) reported successful implementation. Interviews were conducted with representatives from two workplaces that implemented the program after receiving a proposal from their occupational health physicians and one that had yet to implement it. The analysis identified "Relative Advantage, Tension for Change," and "Implementation Climate" as high-priority facilitators and barriers during the Pre-Proposal Internal Setting phase. During the proposal, additional factors such as "trialability," "formally appointed internal implementation leaders," "self-efficacy," and "relative priority" were extracted. Based on the ERIC framework, "Create a Learning Collaborative," "Make Training Dynamic," "Shadow Other Experts," and "Identify and Prepare Champions" were selected as feasible implementation strategies. CONCLUSIONS This study identified facilitators and barriers to introducing participatory workplace environmental improvement programs. Findings suggest that part-time occupational health physicians should provide educational materials and opportunities to build confidence among internal implementation leaders in client companies. Further research should incorporate more on-site practitioner feedback to refine implementation strategies and evaluate their effectiveness.