This study compared components of motor proficiency and physical fitness in adolescents with and without autism spectrum disorders, and assessed the associations between the two measures within each group. A total of 62 adolescent males with (n = 31) and without (n = 31) autism spectrum disorders aged 10–17 years completed the Bruininks–Oseretsky Test of Motor Proficiency (2nd ed.), the BROCKPORT Physical Fitness Test, and the bioelectrical impedance analysis. The main findings are as follows: (1) adolescents with autism spectrum disorders had significantly lower scores on all motor proficiency and fitness measures, except body composition, than adolescents without autism spectrum disorders and that (2) the types of associations between the two measures differed significantly across the groups. Specific interventions to maximize motor proficiency and physical fitness in adolescents with autism spectrum disorders are urgently needed.