Background/Objectives: Eye–foot coordination is essential in sports and daily life, enabling the synchronization of vision and movement for tasks like ball control or crossing obstacles. This study aimed to examine both the validity and reliability of an innovative eye–foot coordination (EFC) test in a dual-task paradigm in children aged 6–11 years and the capacity of this test to discriminate between sex and age. Methods: A total of 440 schoolchildren aged 6–11 years participated in this cross-sectional study. A ball control test, involving kicking and catching, was used to assess EFC. The assessment included three conditions: without interference (WI), with auditory interference (AI), and with visual interference (VI). Results: The ICCs per the EFC test scores were 0.975 for foot successes (95% CI = 0.961–0.983; p < 0.001) and 0.747 for foot mistakes (95% CI = 0.611–0.835; p < 0.001). The SEM for the standing successes was 3.082 (10.81%), and the MDC was 4.860 (17.05%). For the standing mistakes, the SEM was 1.551 (19.33%) and the MDC was 3.452 (43.04%). Moreover, boys had a significantly higher number of successes in the WI, AI, and VI conditions (p < 0.001, respectively) than girls, although girls had more mistakes than boys only in the VI condition (p = 0.025). Conclusions: The EFC test showed adequate reliability and validity. Also, the EFC test showed that performance worsened with interference regardless of sex and age, especially in girls in the VI condition.