Physical exercise has demonstrated its effectiveness in the management of the deleterious process of aging. However, it is less studied in institutionalized elderly people. This investigation aims to clarify the benefits of a multicomponent training program in institutionalized older adults. A randomized controlled trial was conducted with institutionalized older adults (≥ 70 years old). Intervention group (IG; N = 18) were submitted to a multicomponent training program based on muscle power training and interval endurance exercise, 2 times/week for 12 weeks. Control group (CG; N = 16) continued their usual mobility exercises. Independence was estimated with the Barthel index, and physical fitness and functional mobility were evaluated by the Short Physical Performance Battery (SPPB), the Timed Up and Go (TUG) test, the 6-min Walking Test (6'WT), the 10-Meter Walking Test (10MWT), hand grip strength dynamometry, and lower limb muscle strength and power. The IG improved, compared with the CG, in TUG scores in -7.43 s (95% IC: 3.28, 11.59; p < 0.001); in 10MWT scores in -5.19 s (95% IC: 1.41, 8.97; p = 0.004) and -4.43 s (95% IC: 1.14, 7.73; p = 0.002), 6'WT scores in + 54.54 m (95% IC: 30.24, 78.84; p < 0.001); and SPPB in + 2.74 points (95% IC: 2.10, 3.37; p < 0.001). Maximum muscle power and maximum strength did not show statistically significant differences. The multicomponent training program based on muscle power and interval endurance exercise was shown to be safe, well tolerated and effective for the improvement of functional mobility and physical fitness, but not for independence in institutionalized older adults.