Cognitive flexibility (CF) is the ability to shift between concepts or rules. Difficulty with CF is associated with autism (i.e., ASD) as it contributes to repetitive behaviours. However, little is known about CF skills of autistic adolescents with low intelligence. This study uses the Wisconsin Card Sorting Task (WCST) to assess the CF of 36 adolescents, all with a Weschler full-scale IQ between 50 and 85, 14 of whom had an ASD diagnosis. The results indicated no statistically significant differences in WCST performance between those with and without ASD. It was also found that performance IQ significantly contributed to the WCST performance in the ASD group only, suggesting an autism-specific role of non-verbal cognitive functioning in CF.