Creativity is key in developing students' environmental competence so that they come up with working and sustainable solutions to address environmental issues in daily life. However, these remain under-investigated in both Environmental Education (EE) and Education for Sustainable Development (ESD) research. Here, we report an action research study conducted in a Greek kindergarten, supporting and exploring little-c creativity in a group of preschool students during an art-based EE/ESD project. Visual art had a two-fold role in the study: it was applied as the pedagogical approach in the project and also functioned as a complementary art-based research method, to focus on the conditions that enable young learners' creativity within an educational intervention. The findings show that preschoolers' creative thinking is enhanced when encouraged to identify environmental problems in their school and leads to actions towards sustainability. This supports the idea that creativity in preschool EE and ESD requires a pedagogical framework that is receptive to innovation, alongside a supportive teacher who incorporates imaginative, collaborative and reflective approaches to unfold and develop students' creative potential.