Oral health significantly impacts the quality of life, particularly in vulnerable populations such as children with intellectual disabilities (ID). Existing oral health-related quality of life (OHRQoL) instruments often fail to address the unique challenges faced by these children. This study aimed to develop and validate a novel instrument tailored to assess OHRQoL in intellectually disabled children aged 12-18 years. The instrument was developed through a comprehensive process involving a literature review and thematic analysis of qualitative interviews with 22 mothers of intellectually disabled adolescents. Content validity was assessed using a panel of five experts from paediatric dentistry, public health dentistry, and research. Content Validity Ratio (CVR) and Content Validity Index (CVI) methods were employed to evaluate individual items and overall scale validity. Items with CVR ≥ 0.99 and I-CVI ≥ 0.78 were retained. Out of 39 items, 37 achieved a CVR of 1.00, indicating strong consensus on their relevance. The overall S-CVI/UA was 0.864, and S-CVI/Ave was 0.986, reflecting excellent content validity. Two items with CVR scores of 0.2 were excluded. The overall clarity, relevance, and comprehensiveness scores were 2.89, 2.87, and 2.89, respectively. The instrument demonstrates excellent content validity and comprehensively addresses oral health-related quality of life (OHRQoL) challenges in children aged 12-18 years with intellectual disabilities in the Pondicherry City, India. However, considering potential cultural and age-related differences, further studies are warranted to validate its applicability across diverse populations and younger age groups.