Anxiety problems are common disorders in children and later ages. People with anxiety disorders need to be treated by psychological methods. The aim of the present study was to determine the effectivness of Mindfulness-Based Cognitive Therapy (MBCT) on self-esteem, self-concept, and social anxiety of people with social anxiety disorder. The participants in this study were 30 individuals with social anxiety disorder who referred to counseling and psychotherapy centers in Shiraz during April to July 2021 (experimental group: 15, control group: 15). The experimental group received 8 sessions of MBCT training, once a week for 120 minutes over 56 days and the control group received no interventions. Results of covariance analysis for the effect of MBCT treatment on self-esteem (F=32, P=0.001), self-concept (F=38, P=0.001), and social anxiety (F=48, P=0.001) showed a significant difference between the experimental and control groups. Results of the present study showed that MBSR therapy could be useful in patients by increasing their self-esteem and self-concept and also reducing social anxiety.