Detecting and managing frailty at early stages can prevent disability and other adverse outcomes. The study aim was to evaluate whether a multifactorial intervention program could modify physical and cognitive frailty parameters in elderly individuals. We conducted a multicenter, randomized, single-blind, parallel-group trial in community-living prefrail/frail elderly individuals in Barcelona. A total of 352 patients, aged ≥65 years old with positive frailty screening, was randomized into two groups to receive a 12-week multidisciplinary intervention or usual care, with concealed allocation. The intervention consisted of: exercise training, intake of hyperproteic nutritional shakes, memory training, and medication review. Main outcome assessments with multivariate analysis were conducted at 3 and 18 months. A total of 347 participants (98.6%) completed the study, mean age 77.3 years, 89 prefrail subjects (25.3%), and 75.3% female (n = 265). Eighteen-month assessments were performed in 76% of the sample. After 3 and 18 months, adjusted means difference between-groups showed significant improvements for the intervention group in all comparisons: Short Physical Performance Battery score improved 1.58 and 1.36 points (p < .001), handgrip strength 2.84 and 2.49 kg (p < .001), functional reach 4.3 and 4.52 cm (p < .001), and number of prescriptions decreased 1.39 and 1.09 (p < .001), respectively. Neurocognitive battery also showed significant improvements across all dimensions at 3 and 18 months. A physical, nutritional, neurocognitive, and pharmacological multifaceted intervention was effective in reversing frailty measures both at short-term and 18 months. Lasting benefits of a multi-intervention program among frail elderly individuals encourage its prioritization.