Biological age, which represents the degree of maturity of an organism, can vary among children of the same chronological age, leading to differences in their motor development. One of the challenges in karate, as well as in many other combat sports, is the competitive aspect that involves dividing athletes into different categories. These categories are organized according to chronological age, but in matches, there is also a division based on the body weight of the athletes. This division creates a problem similar to that in other sports: children of the same chronological age can significantly differ in biological age, which can affect their performance. The primary aim of the study was to determine the relationships between biological maturation and the performance of fundamental motor skills in young karate practitioners. The sample of respondents in this study consisted of 60 children aged 8 to 11 years, including 25 boys and 35 girls. All respondents were members of karate clubs from Dalmatia, and their training experience was approximately one year. With the help of measured anthropometric variables, variables such as bone age, age at peak height velocity (APHV), and current distance from APHV were calculated according to two authors: Moore and Mirwald. The "Test of Gross Motor Development 2" was used to assess motor skills. Initially, a significant difference between the chronological and bone ages of the respondents was established. Furthermore, the results of the correlation analysis suggest that there are no significant associations between bone age and the level of fundamental motor skills. In conclusion, this research confirms that children's motor development is a multifactorial process that requires careful monitoring and tailored interventions. Although biological age in itself may not be crucial for the development of fundamental motor skills, its monitoring in combination with other relevant factors can provide valuable information for optimizing the development of motor skills and overall health of children.