Education for Sustainable Development (ESD) is a demanding new field in terms of content and context and requires whole-school approaches and changes in educational structures. The field's implementation constitutes a great challenge for teachers, novice in the field of ESD. Teacher education for ESD needs to effectively transfer knowledge and skills related to the concepts of sustainable development and reflect the relation of ESD to values education, systemic thinking and an interdisciplinary approach. The teaching methods employed by teacher education need to be in accordance with ESD methods and to empower teachers for integrating ESD in the teaching--learning process. For this purpose, we used a mentoring system to introduce experienced and newly appointed teachers, all novice in the field of ESD, to planning and implementing ESD and evaluated the potential of mentoring as a form of education for empowering teachers for ESD. Results highlight the value of mentoring since it encompasses all of the attributes that ESD teacher education requires in an experiential and practical form, it promotes teacher interaction and the formation of professional learning communities for ESD and it increases teachers' pedagogical content knowledge of the subject.