The research aim was to obtain a Sociocultural Theory-oriented Mathematics Learning Model with "Tri Hita Karana" insight that is valid, practical, and effective in developing the good character of students in learning mathematics. This research was a research and development with reference to the development of Plomp. The data collection techniques used tests and questionnaires. The results showed that: (1) the Sociocultural Theory-oriented Mathematics Learning Model with "Tri Hita Karana" insight is valid, practical, and effective to use to develop the good character of students; (2) there was an increase in the good character of students from the category 'sometimes shows good behavior according to the "Tri Hita Karana" aspect and often behaves not in accordance with the "Tri Hita Karana" aspect' to the category 'often and consistently shows good behavior according to the "Tri Hita Karana" aspect'; and (3) positive student responses to learning.