Even before the onset of the COVID‐19 pandemic, researchers had raised concerns about the mental health of youth worldwide. One response has been the development of positive psychology interventions (PPIs) designed to enhance well‐being. This study, conducted at a Thai university, investigated the impact of an online positive psychology course containing several PPIs on student well‐being as measured by the EPOCH Measure of Adolescent Well‐Being, the Satisfaction With Life Scale (SWLS), and Subjective Happiness Scale. The scores of the students in the positive psychology course (n = 84) increased in all areas measured, with statistically significant increases in the Perseverance, Optimism, and Happiness subscales of the EPOCH. Meanwhile, the scores of the control group (n = 105) decreased in all but two areas, with statistically significant decreases in the SWLS and Optimism. These findings suggest that teaching PPIs online can positively impact students' well‐being.