Adhering to the basic principles of transformative learning in education for sustainable development, socioemotional competencies are fundamental for the promotion of sustainability; however, they are difficult to nurture. There is initial evidence that mindfulness practice may promote the enhancement of such competencies, but a comprehensive analysis of how mindfulness practices could be nurtured and a measurement of its effectiveness in developing this set of competencies are missing. This paper aims to fill this gap by synthesizing the findings of current research on the effectiveness of mindfulness programs for the promotion of socioemotional competencies. By performing a systematic review and a meta-analysis, this paper shows that mindfulness practices, although they have a weak effect, could be an effective method to positively influence three outcomes of socioemotional competencies: emotional regulation, empathy and social connectedness, and resilience with differential effects. Guidance is also offered to implement mindfulness practices to successfully enhance ESD.