Early Childhood Education and Care (ECEC) places value and benefits on children’s play in nature-based outdoor spaces. However, there is a lack of knowledge regarding teachers’ support of play in environments with rugged terrains and natural materials. Therefore, this systematic review aims to locate, present, and discuss research literature on how teachers in ECEC settings can support children’s play in nature-based outdoor spaces. According to the review, teachers’ support of children’s play was described in the literature as encouraging children’s free and unstructured play through facilitating actions addressing the children’s perspectives and the opportunities offered by the physical environment. Furthermore, teacher support was also described as teacher-led and teacher-guided interactions where teachers and children communicate or collaborate in playful situations. Differences and overlapping elements of types of teacher support are discussed, and implications for researchers, practitioners, and ECEC teacher education are provided.