Early childhood education [ECE] in Spain is voluntary and divided into two stages: from 0 to 3 years and from 3 to 6 years. Although the second stage has an enrolment rate exceeding 97%, the transition to primary education [PE] presents challenges due to methodological and curricular differences between ECE and PE. A systematic review of 30 published Spanish studies analysed the characteristics and findings of research on transition to primary education. Qualitative methodological approaches predominate, with a growing trend to involve pupils directly through adapted techniques. The findings highlight discrepancies between teachers and families, the need for pedagogical strategies that promote the active participation of pupils, and the importance of considering children’s perspectives. The conclusion highlights the need for flexible approaches adapted to each educational context, fostering consistent pedagogical practices and collaboration among all stakeholders. Emphasis is placed on raising awareness among families, training teachers, respecting individual rhythms, and designing welcoming learning environments. Universal solutions are discouraged, advocating instead for adaptation to the specific needs of each educational community to facilitate a successful transition from ECE to PE.