The Montessori method was originally developed from an examination of children with cognitive disabilities. Numerous studies have explored the application of Montessori principles with typically developing children and adolescents across different educational settings. However, despite its original interest in children with cognitive disabilities, there has been a limited number of systematic reviews specifically addressing its impact on these children. We conducted a systematic review of quantitative research based on a search of the literature on the effects of the Montessori educational approach in teaching academic and non-academic skills to children and young people with intellectual disabilities (IDs) and autism. A search was conducted of seven bibliographic databases: Embase, PubMed/MEDLINE, PsycINFO, Cochrane Library, Ebscohost, Proquest, and Scopus, until 31 October 2024. We identified 7165 reports, 3 of which meet the inclusion criteria for the review. The selected studies reported improvements in the areas investigated, including motor skills, perceptual abilities, cognitive development, and self-care, confirming the effectiveness of the Montessori methodology. Although there are few experimental studies available, these findings provide valuable operational insights. They suggest that we can return to the roots of the method, which was originally designed for children with mental disorders. An experimental approach to this time-honored method could enhance its application in neurodevelopmental disorders, maximizing autonomy and inclusion while improving the quality of life for individuals with disabilities.