BACKGROUND: The aim of this randomized wait-list controlled trial was to explore the effects of Mindfulness-Based Cognitive Therapy (MBCT) on risk and protective factors for depressive relapse within the domains of cognition, emotion and self-relatedness. METHODS: Sixty-eight individuals with recurrent depressive disorder were randomized to MBCT or a wait-list control condition (WLC). RESULTS: Completers of MBCT (N = 26) improved significantly on measures assessing risk and protective factors of recurrent depression compared to WLC (N = 30) on measures of rumination (d = 0.59, p = .015), emotion regulation (d = 0.50, p = .028), emotional reactivity to stress (d = 0.32, p = .048), self-compassion (d = 1.02, p < .001), mindfulness (d = 0.59, p = .010), and depression (d = 0.40, p = .018). In the Intention To Treat sample, findings were attenuated, but there were still significant results on measures of rumination, self-compassion and depression. CONCLUSIONS: Findings from the present trial contribute to evidence that MBCT can lead to reduction in risk factors of depressive relapse, and strengthening of factors known to be protective of depressive relapse. The largest changes were found in the domain of self-relatedness, in the form of large effects on the participants' ability to be less self-judgmental and more self-compassionate. TRIAL REGISTRATION: ISRCTN, ISRCTN18001392. Registered 29 June 2018.