Background: Down syndrome is a condition caused by a genetic anomaly that impacts the physical and intellectual development of individuals. A significant number adopt a sedentary lifestyle, potentially due to such health conditions or the lack of guidance and support from healthcare and fitness professionals. Objective: To analyze the effects of strength training in young individuals with Down Syndrome. Methods: This systematic review was conducted following the recommendations outlined by PRISMA and registered on the PROSPERO platform (xxxxxxxxxxxxxx). The PICOS acronym was used to define eligibility criteria. The databases searched included MEDLINE (PubMed), Scopus, and Web of Science using the following phrase: (((resistance training[Title/Abstract]) OR (strength training[Title/Abstract])) AND (down syndrome[Title/Abstract])) OR (Trisomy 21[Title/Abstract]). Results: 911 articles were retrieved. Following screening, three randomized clinical trials meeting the specified criteria were included for analysis, comprising a total of 114 participants, with 57 in each group. The included articles were deemed to have low risk of bias according to the RoB 2.0 tools and achieved a minimum score of 12 points on the TESTEX tool. Conclusions: Strength training can significantly improve muscle strength in children and young individuals with Down syndrome, promoting functional independence and social integration.