Abstract: Green development in ecological conservation areas is an important practice for addressing the coexistence of ecological constraints and development needs. Based on household survey data from Mentougou District, Beijing, this study constructed an analytical framework of “institution–behavior–outcome” to examine the effects of policy support, market characteristics, and other factors on the adoption of green technologies and the transmission of their performance outcomes. The results showed that policy support significantly promoted farmers’ adoption of green technologies, while technical training also played a positive role. Sales channel diversification strengthened incentives for green technology adoption, but no significant interaction effect was found between sales diversification and policy support. Green technology adoption had not yet been significantly translated into farmers’ perceived improvements in income or ecological conditions. Cognitive factors, including expected green returns, policy perception, and ecological concern, exerted a stronger influence on farmers’ subjective performance evaluations, and institutional effects were mainly observed among farmers with higher levels of policy perception. Accordingly, policy efforts should focus on improving the policy support system, deepening green production technology training, strengthening the value realization of ecological products, and enhancing the cognitive feedback mechanism of green transformation, so as to continuously advance green development in ecological conservation areas.