Background Mindfulness-based interventions (MBIs) are potentially effective psychological interventions for people with anxiety disorders. However, the effectiveness of MBIs for obsessive–compulsive disorder (OCD), a psychiatric diagnosis distinct from anxiety disorders in the fifth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5), is uncertain. Methods A systematic review was conducted to examine the effectiveness of MBIs for people with OCD. Six electronic databases were searched from inception to March 2021 to identify relevant articles. The primary outcome was the severity of obsessive–compulsive symptoms. Results Ten studies involving 625 participants were identified. The results of the meta-analysis demonstrated a significant, small to medium, pooled effect of MBIs on reducing obsessive-compulsive (SMD = −0.35) and depression symptoms (SMD= −0.32), and improving mindfulness skills (SMD= 0.49) at immediately post-intervention when compared with control group. Subgroup analysis reported that the superiority of MBIs over control on OCD symptoms was significant only in the self-rated scales (i.e., OCI-R) but not in the clinician-rated interview (i.e., Y-BOCS). Conclusions This was the first systematic review to synthesize research evidence on the effectiveness of MBIs for OCD patients. Our findings suggest that MBIs are promising to be an effective adjunct treatment for patients with OCD.