This study aimed to investigate the effects of a 12-week self-selected resistance training (SSRT) program on physical fitness and psychophysiological responses among physically inactive older women. We randomly allocated 32 inactive older women (M age = 66.0 years, SD = 3.0) into either an SSRT (n = 16) or control group (n = 16). Participants performed SSRT three times per week over 12 weeks. We assessed maximal isotonic and isokinetic muscle strength, functional capacity, flexibility, cardiorespiratory fitness, and body composition at baseline and after the intervention. Affective responses and perceived exertion were evaluated after each exercise set throughout the training program. The SSRT group significantly improved their maximal muscle strength in all exercises (Cohen’s d ranging from 1.4-3.3; all p’s < .001), peak torque (knee flexors: d = 1.7; knee extensors: d = 1.6; all p < .001), flexibility (knee flexors: d = 1.7; single hip flexors: d = 1.6; all p < .001; bilateral hip flexors: d = 1.1, p = .001), fat-free mass (d = .9, p = .008), and cardiorespiratory fitness (d = .9, p = .014), compared to the control group. All components of functional capacity improved compared to the control group (Cohen’s d ranging from .8 to 5.5; all p’s ≤ .001). Participants perceived the exercise training sessions as pleasant and of low to moderate effort. Thus, a 12-week SSRT program was effective at improving physical fitness and inducing feelings of pleasure among inactive older women.