This study aims to identify the effectiveness of mindfulness intervention on the psychological behaviors of adolescents with parental HIV infection and its associated factors in Myanmar. A total of 80 adolescents from 2 intervention townships and 80 adolescents from 2 control townships were enrolled in a group randomized controlled trial with assessments at baseline and 6 months follow-up. The mindfulness intervention involved monthly group sessions for 3 consecutive months led by an experienced mindfulness trainer. Three domains of psychological behaviors-namely, emotional, conduct, and social behaviors-were assessed at baseline and compared after 6 months. Multilevel regression analysis was used to determine the effectiveness of the intervention and associated factors for psychological behaviors. The intervention significantly improved emotional and conduct behaviors at 6 months (P < .001) but had no effect on social behavior. The significant effect of the intervention existed after adjusting for gender, family type, child age, and orphan status.