Whole-body electromyostiulation (WB-EMS) has experienced a boom in recent years, even though its effectiveness is controversial. A sedentary lifestyle is deeply rooted in the European population, mainly in the elderly. This experimental study analyzed the impact of WB-EMS on the physical fitness of postmenopausal women. Thirty-four healthy sedentary women between 55 and 69 years followed an experimental design pre–post-test. Both groups conducted a ten-week aerobic and strength training program. The experimental group overlaid the WB-EMS during exercise. At the end of the intervention, both groups improved upper and lower body strength, lower extremity flexibility, agility, and speed levels (p_Bonferroni < 0.05). Significant interactions were observed at upper and lower body strength, agility, speed, and cardiovascular endurance (p < 0.05). The WB-EMS group scored better agility than the control group at the end of the intervention (p_Bonferroni < 0.05) and was the only group that improved cardiovascular endurance. WB-EMS shows a favorable isolate effect on the development of dynamic leg strength, agility, and cardiovascular endurance but did not in dynamic arm strength, gait speed, balance, or flexibility of postmenopausal women.