Education for Sustainable Development (ESD) is an important issue for the education of students worldwide because it offers knowledge, skills, attitudes and values necessary to ensure a sustainable future for humanity at local and global levels, which is nowadays becoming critical. The decade 2005-2014 called 'Decade of ESD' was an initiative by the United Nations to promote ESD worldwide, followed currently by the Agenda 2030. ESD should be an ongoing subject for students in formal and informal education, at all educational levels, and in life-long learning programs, starting with early childhood education. This paper reports on the knowledge, perceptions and attitudes of pre-service early childhood teachers of the University of Ioannina, Greece, on ESD using a quantitative approach utilizing a questionnaire. Our findings showed that most pre-service teachers had knowledge on environmental aspects but did not consider societal and financial matters to be aspects of ESD. Furthermore, most students had never ESD lessons during their formal education. Our findings depict that pre-service teachers believe that ESD is an important issue, that it should be included in the curricula and that lessons on EDS during their studies would develop their ability to teach ESD to their students.