This randomized controlled trial compared the effects of 1v1 and 3v3 basketball small-sided games (SSGs) on body anthropometric-related outcomes and physical fitness in sedentary female college students. Sixty-three sedentary female university students aged 18-21 years were randomized to 1v1 SSGs (n = 21), 3v3 SSGs (n = 21), or a non-training control group (n = 21) for 8 weeks. Training was performed three times per week, with each 60-min session including 40 min of SSG play. Outcomes were assessed at baseline, week 4, and week 8. All randomized participants completed the scheduled assessments, with no missing outcome cases. Adherence was 94.5% in the 1v1 group and 92.8% in the 3v3 group. The primary outcome was 20-m multistage fitness test distance. Secondary outcomes included body mass, body mass index, waist circumference, hip circumference, waist-to-hip ratio, the sum of skinfold thicknesses, handgrip strength, vertical jump height, and standing long jump distance. Linear mixed-effects models including group, time, and group × time were used to estimate longitudinal intervention effects. The primary outcome improved more in both intervention groups than in the control group. The 20-m multistage fitness test distance increased by 29.1% in the 1v1 group and 35.3% in the 3v3 group, compared with 1.1% in the control group; the model-estimated differences in baseline-to-week 8 change versus control were 120.95 m for 1v1 and 151.43 m for 3v3, with both Holm-adjusted p values < 0.001. Body mass decreased by 6.8% in the 1v1 group and 8.2% in the 3v3 group, compared with 0.8% in the control group. The corresponding differences in baseline-to-week 8 change versus control were -3.45 kg for 1v1 and -4.18 kg for 3v3, both with Holm-adjusted p values < 0.001. The sum of skinfold thicknesses decreased by 10.6% in the 1v1 group and 12.2% in the 3v3 group, compared with 0.4% in the control group (p values < 0.001). Secondary fitness outcomes also improved more in the intervention groups than in the control group, including handgrip strength, vertical jump height, and standing long jump distance. The 3v3 format showed larger exploratory gains than 1v1 in vertical jump height and standing long jump distance, whereas direct between-format differences for multistage fitness test distance and handgrip strength were not statistically significant. Eight weeks of recreational basketball SSGs improved cardiorespiratory fitness, several adiposity-related indicators, and neuromuscular fitness in sedentary female college students. These findings support basketball SSGs as a reasonable university-based exercise strategy, although between-format comparisons should be interpreted cautiously because they were exploratory. Future studies should test these formats in larger multicenter samples, include longer-term follow-up, and incorporate dietary/free-living activity monitoring and direct training-load measures to clarify sustainability, mechanisms, and format-specific effects.