Nutritional intervention is increasingly being recognized as playing an important role in functional status. The supplementation with β‑hydroxy-β-methylbutyrate (HMB), which is a metabolite of an essential amino acid, may be an effective nutritional intervention to improve muscle strength and functionality in older adults. The aim of this narrative review was to present an updated overview of the effects of HMB supplementation in older adults, specifically on muscle strength and functional outcomes. A PubMed database search was performed and only randomized controlled trial studies were included. More than half of the 14 analyzed studies reported that HMB supplementation improved muscle strength and other functional outcomes. HMB supplementation has demonstrated some promising effects on muscle strength and functional outcomes in older adults with different conditions of health and physical activity.