In response to the full-scale implementation of the High School Credit System in Korea, this study examines the "Joint Curriculum between High schools and Local Institutions" as a potential alternative for securing subject diversity. Through in-depth case analyses of District J and K, where such programs are actively operated, the study explores the collaborative processes involved and identifies their distinctive characteristics. The findings are as follows. First, a common collaborative process was identified, with the preparation phase marked by the establishment of cooperative governance based on a "Win-Win strategy." Second, from an implementation perspective, the Joint Curriculum provided field-oriented lectures and enhanced students’ understanding of their local communities. This is expected to foster a sense of responsibility and community toward their hometowns and contribute to regional revitalization. Third, in terms of evaluation and feedback, a relatively flexible assessment system was observed, reflecting the program’s early-stage implementation and the need for stable institutionalization. Lastly, the curriculum’s successful operation depended on specific preconditions, such as the density of participating institutions, support from local governments, and the ability to meet the needs of local schools. Based on these findings, this study suggests the development of policies that reflect the unique characteristics of high school–local institution collaboration, considers its potential as a strategy for local revitalization, and emphasizes the importance of designing implementation methods that are sensitive to regional contexts.