A significant change in the lifestyle of modern children associated with the active use of digital devices in educational and leisure activities can affect their psychomotor development. The study aimed to assess the effect of using smartphones and computers on psychomotor function indicators in primary school students. A questionnaire survey of 333 parents of the 1−4-year students attending Zemskaya Gimnasia in Balashikha on issues of children's life was conducted. The students’ screen time when using a computer and smartphone throughout the day and week was estimated. To assess the students’ psychomotor functions, the Little House test and motometric test conducted by teachers were used. Assessment of the effect of computer use on psychomotor development indicators revealed a correlation. Thus, when using a computer, a deterioration in fine motor skills was noted; the correlation coefficient (r) for the parameters of visual-motor coordination and the duration of computer use per day was 0.320 (p = 0.002). The correlation coefficient for the duration of computer use and the primary school students’ final psychomotor development score was 0.235 (p = 0.028). The same result was obtained for the integrated assessment of fine motor skill development and its association with the duration of computer use per day: r = 0.253 (p = 0.025). However, there was no correlation between screen time when using a smartphone and psychomotor functions. The findings can be used in the development and justification of preventive technologies to prevent the negative impact of digital devices on the development of psychomotor functions in children, especially at the initial stage of systematic education.