Purpose: This study aimed to investigate the effects of online high-intensity interval training (HIIT) in abdominally obese women experiencing health complications due to COVID-19. Methods: Sixteen participants were enrolled and divided into the HIIT group (n = 8) and moderate-intensity continuous training (MICT, n = 8) group. The HIIT group underwent 20 min of exercise consisting of 20 s of high-intensity (85–90% HRmax) exercise followed by 30 s of exercise at 60% HRmax using only body weight. The main exercise program for the MICT group included 40 min of stationary bike pedaling at 65–70% HRmax. Exercise was performed three days a week for eight weeks using a smart device and application that enables bidirectional communication. Results: The HIIT group showed reduced body fat (p = 0.036), BMI (p = 0.021), and visceral fat (p = 0.003) compared to the MICT group. Further, the HIIT group also had reduced insulin (p = 0.021) and LDL levels (p = 0.024), increased grip strength (left p = 0.012, right: p = 0.002), and a substantial drop in total stress index (p = 0.004) compared to the MICT group. Conclusions: Thus, online HIIT is a useful means to reduce abdominal fat, improve blood lipid profile and muscle strength, and relieve stress caused by COVID-19.