The purpose of this study was to investigate the effects of biological maturity and relative age on physical fitness and sport-specific skills in young futsal players. The study included 58 male athletes in the age group of 12 years who participated in futsal games in school sports. The age of the study group was 12.57 ± 0.26 years, the average height was 158.74 ± 8.48 cm, and the body weight was 50.15 ± 9.25 kg. After determining the relative age, maturity status, height, and body weight of the study group according to their birth months, they were asked to participate in a hand strength test, a vertical jump test, a sit-stand test, a 30-metre sprint test, a 505 mobility test, a push-up test, and a sit-up test. A significant difference was found in the values of height, body weight, right and left hand grip strength, vertical jump test, sit-stand flexibility test, 30 m sprint test, 505 agility test, push-up test, and sit-up test in young male futsal players who were born in the first months of the year and matured early compared to athletes who were born in the last months of the year and matured late. As a result of our study, it was found that futsal players born in the first months of the year or matured early were taller and heavier than futsal players born in the last months of the year or matured late. It was also found that these athletes have better performance scores than their peers born in the last months of the year or matured later.