Adolescents who have a sibling with developmental disabilities were more likely to have more challenges and unpleasant emotions compared to adolescents who have a sibling without developmental disabilities. Besides, the sibling relationships with developmental disabilities siblings were most likely to be affected negatively due to the deficits in cognitive, language, and social skills. Due to the challenges and unpleasant emotions among adolescents with disability siblings, this study was aimed to identify the coping strategies and sibling relationships of the adolescents with developmental disabilities siblings in Malaysia. Besides, this study also aimed to evaluate the perceptions of the adolescents who have a sibling with developmental disabilities in the family functioning. This study was conducted using qualitative research with phenomenological design on 10 participants. The participants were recruited through purposive sampling methods and data were obtained by conducting semi-structure interviews. Based on the result, the most common coping strategies used by the adolescents who have a brother or sister with developmental disabilities were emotional-focused coping strategies. Half of the adolescents reported positive sibling relationships with their brother or sister with developmental disabilities, another half of the adolescents were not. Besides, most of the adolescents perceived poorer communication, problem-solving, decision making, and less satisfaction of leisure time in the family. Therefore, parental training or counselling should be provided to the family who have a child with developmental disabilities to help the family, included the adolescents to have better coping strategies and sibling relationships to overcome the difficulties.