Exercise has been suggested for older adults. However, there is no consensus whether exercising older adults present better strength levels and body composition indexes compared with inactive counterparts. Our aim was to compare absolute and relative isokinetic muscular knee strength and body composition between exercising and non-exercising older women. Exercising (n = 20) and non-exercising (n = 21) groups were evaluated for body mass index (BMI), body composition, and isokinetic muscular knee strength. BMI (p = 0.005), total body mass (p = 0.01), fat mass (p = 0.01), and fat mass percentage (p = 0.01) were higher in non-exercising women, and the lean mass percentage was lower in the non-exercising group (p = 0.01). Isokinetic extensor and flexor knee muscle strength for dominant limbs presented higher peak torque values when corrected for total body mass (Nm·kg−1) in the exercising group (p < 0.05). Exercising older women presented better body composition and higher strength relative to total body mass, but not maximum absolute strength.