Obstructive sleep apnea (OSA) is common in children with Down syndrome (DS). Adenoidectomy and/or tonsillectomy are the usual first interventions employed to treat OSA in children with DS but sometimes do not achieve adequate resolution of clinical signs. Positive airway pressure treatment is often used next, but this treatment is poorly tolerated by this population. Persistent OSA can adversely affect a child's health and cognitive development. Hypoglossal nerve stimulation (HGNS), previously shown to be safe and effective in adults with OSA, has been used in children as young as 10 years old with DS and has achieved measurable neurocognitive benefits. The US Food and Drug Administration recently lowered the age for HGNS implantation to 13 years for children with DS. However, questions remain regarding treatment of refractory OSA in younger children. Here, we report the case of a 4-year-old boy with DS and treatment-refractory OSA who underwent successful HGNS implantation. The decision to proceed with HGNS implantation in such a young child involved discussions about anatomic feasibility and potential neurocognitive benefits. The device was implanted without complication and with minimal postoperative bulk. This case suggests a possible treatment option that can be discussed in the course of shared decision-making between clinicians and families of young children with DS and treatment-refractory OSA.