Background: Generalised anxiety disorder (GAD) has harmful effects on physical and mental health and quality of life. Mindfulness-based cognitive therapy (MBCT) is a treatment option for GAD. This meta-analysis was conducted to determine the effectiveness of MBCT on GAD. Methods: Two authors independently performed the eligibility, quality assessment, and data extraction processes, and consensus was reached in case of discrepancies. Electronic databases were searched for eligible studies (randomised controlled trials, randomised trials, cluster randomised controlled trials, and clinical trials) up to November 2018 using keywords: mindfulness-based cognitive therapy OR mindfulness based cognitive therapy OR MBCT AND general anxiety disorder OR GAD*. The methodological quality of studies was assessed using the revised Jadad scale. Cohen's formula was used to determine the effect size based on the mean and standard deviation of the changes in the study groups before and after the intervention. Results: Six studies that compared the effectiveness between MBCT and controls were included for analysis. The mean revised Jadad score of the six studies was 4.3 (range, 3-6). The overall mean effect size was -0.65. The funnel plot of effect sizes in relation to the effect size standard error showed a symmetrical distribution. Compared with controls, MBCT significantly improved the treatment outcome of GAD in all studies, except one. Conclusion: MBCT was effective for treating GAD.