Research has shown that mindfulness-based interventions are effective in promoting well-being of clinical populations. However, limited research has been conducted to examine the effectiveness of mindfulness-based interventions for teachers. Furthermore, existing mindfulness-based interventions have mostly focused on the practical element of mindfulness without giving proper attention to its rich existential context rooted in the Buddhist tradition. This study sought to address this gap by developing and evaluating an existential mindfulness program for teachers (EMPT). The EMPT consists of two components: (1) the practical component, which involves various kinds of guided mindfulness meditation; and (2) the existential component, which involves exploration of existential concerns at a personal level. The program was specifically designed to improve teachers’ mindfulness and well-being and reduce their ill-being. A mixed-methods research design was employed. For the quantitative part, the research questions focused on examining whether EMPT increased mindfulness and well-being and whether it reduced ill-being. For the qualitative part, the research questions focused on examining the participants’ subjective experiences of the EMPT program, as well as their suggestions to improve the program. The study comprised of two groups of participants. The first group were 15 students who were studying various programs at the university (U Group). The second group was composed of ten teachers recruited from a Kindergarten (KG Group). Questionnaires that measure mindfulness, well-being, and illbeing were administered one week prior to the implementation of the EMPT, and the same questionnaires were administered again one week after the intervention. Paired t-tests were used. For the qualitative part, focus group interviews were conducted at the final sessions of each group. With the U Group, quantitative findings showed that EMPT was effective in partially enhancing key dimensions