Introduction. The article studies the problem of children’s adaptation to systematic learning at primary school, which is significant in a rapidly changing world, determining both the conditions of the educational environment and the requirements for the level of preschoolers’ preparation. The purpose of this study is to evaluate the influence of the level of preschoolers’ cognitive development on their adaptation to systematic learning at primary school. Materials and Methods. The methodology of the study is based on a systematic approach that allows the authors to reveal psychophysiological characteristics of the subject, the complex of which provides the most complete picture of the child’s development. The following methods were used: theoretical analysis, synthesis; diagnostic methods, allowing to assess the level of cognitive development and academic performance of the examined children; methods of mathematical statistics for processing empirical data. Results. Through theoretical analysis and generalization of research data, it is shown that the majority of children have developed basic cognitive functions by the older preschool age. However, carrying out a comprehensive diagnosis of the preschoolers’ functional development in preparatory groups, the authors identified low levels of voluntary regulation, visual-spatial perception and visual-motor coordination in a third of the examined preschoolers. Based on the data analysis of these children’ academic performance at primary school, the authors identified influence of the level of the above mentioned cognitive functions in preschool age on academic performance at primary school. Longitudinal analysis showed a gradual increase in academic performance in this group of students by the third year at primary school. Conclusions. Based on the results obtained, the authors showed that the level of cognitive functions development, as well as social and communication skills, significantly influences the successful adaptation of first-year primary schoolchildren and subsequent academic performance at primary school. In conclusion, the authors point out that it is necessary to conduct a comprehensive assessment of cognitive development in older preschool age in order to identify individual characteristics and predict possible risks of maladjustment at school.