Frailty is associated with negative health outcomes, disability, and mortality. Physical activity is an effective intervention to improve functional health status. However, the effect of resistance training on multidimensional health in frail older adults remains unclear. This randomized controlled trial was conducted in a U.K. residential care home to assess feasibility with limited efficacy testing on health and functional outcomes and to inform a future definitive randomized controlled trial. Eleven frail older adults (>65 years) completed a 6-week machine-based resistance training protocol three times a week. Uptake and retention were greater than 80%. The measures and intervention were found to be acceptable and practicable. The analyses indicated large improvements in functional capacity, frailty, and strength in the intervention group compared with the controls. These findings support the feasibility of a definitive randomized controlled trial and reinforce the value of resistance training in this population. This trial was registered with ClinicalTrials.gov: NCT03141879.