To understand and to enact teachers' practices, these practices must be made visible to pre-service teachers, and this happens through representations. This paper focuses on representations in teacher education, and on representation of lesson planning in particular. Lesson planning is a core practice in teachers' work and a critical component of teacher education curricula. However, there is limited knowledge regarding how planning for mathematics teaching is addressed in teacher education, including how representations of teachers' planning practice are used in the teaching of planning. This mapping review aims to identify the types of representations of lesson planning used in mathematics teacher education as these are visible in research on the development of planning skills for mathematics teaching in primary school. Searches were done in ERIC and Scopus for empirical research studies conducted between 2000 and April 2023 and written in English. After applying inclusion/exclusion criteria, 25 publications were included. Representations made visible in the included studies related to both representations of planning as a process and representations of products of planning. The majority of process-focused representations involved joint planning together with teachers or teacher educators, and product-focused representations involved complete lesson plans by more experienced teachers or teacher educators, or written examples of learner activities/tasks, but also some cases of pre-planning. Overall, there were few studies that addressed the representations used, and future research may benefit from making the use of representations more explicit, as well as exploring how different representations might influence pre-service teachers' learning opportunities and understanding.