The present study aimed to investigate the impact of mindfulness-based cognitive therapy on the psychological capital and behavioral inhibition and activation  of students. This research was a quasi-experimental study with a pre-test and post-test design and a control group. The study population included all fourth-grade elementary school students in Tehran during the 2022-2023 academic year. In this context, 30 students were purposefully selected and divided into two groups of 15, one experimental and one control. To measure the research variables, the Behavioral Inhibition and Activation Systems Questionnaire (BIS/BAS, Carver & White, 1994) and the Psychological Capital Questionnaire (PCQ, Luthans et al., 2007) were used. The experimental group underwent mindfulness-based cognitive therapy intervention over 8 sessions, after which a post-test was conducted for both groups. Data analysis was performed using SPSS version 26, employing descriptive statistical methods (mean, standard deviation, frequency, percentage) and multivariate analysis of covariance. The results showed that mindfulness-based cognitive therapy, controlling for the pre-test effect, had a significant difference between the mean post-test of psychological capital and behavioral inhibition and activation in the experimental and control groups at the p<0.01 level؛ Therefore, it can be concluded that this type of therapy has a significant impact on behavioral inhibition and activation, as well as on the psychological capital of students.