Intellectual disability (ID) affects 1%–3% of the population, while borderline intellectual functioning (BIF) affects 13%–14% of individuals, together representing a substantial burden in pediatric neurology. This review synthesizes current evidence on diagnostic frameworks, genomic advances, and targeted therapeutics relevant to pediatric practice. We reviewed recent literature focusing on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) and International Classification of Diseases, 11th Revision (ICD-11) updates, genomic diagnostic innovations, and emerging therapies identified through PubMed and clinical trial registries (2019–2024). Diagnostic frameworks now emphasize adaptive functioning rather than intelligence quotient (IQ)-based classifications, with severity defined by required support levels rather than cognitive scores. Genomic testing has progressed from chromosomal microarray (10%–20% yield) to trio whole-exome sequencing (30%–45% yield), with professional guidelines endorsing genome-first approaches as first-line testing. Common comorbidities require systematic management, including autism spectrum disorder (15%–20%), attention-deficit/hyperactivity disorder (20%), epilepsy (20%–30% in moderate-to-severe cases), and mental health disorders. Traditional management continues to prioritize early intervention, educational support, and comprehensive medical care, while emerging targeted therapies show clinical benefit, including U.S. Food and Drug Administration-approved trofinetide for Rett syndrome and investigational antisense therapies for Angelman syndrome. Contemporary ID management demands genome-first diagnostic strategies, structured comorbidity assessment, and integration of targeted therapeutics. The BIF population requires formal diagnostic recognition and broader service eligibility. Optimal outcomes depend on collaboration among pediatric neurologists, geneticists, and developmental specialists through precision-medicine–based approaches.