<b>Background/Objectives:</b> The risk of sarcopenic obesity across menopausal transition stages remains unclear. This study investigated the association between menopausal stage and the risk of sarcopenic obesity. <b>Methods:</b> This longitudinal study included 4766 Korean women aged 42-52 years (median follow-up duration, 9.1 years). Menopausal transition was classified by STRAW + 10 stages: premenopause, early transition, late transition, and postmenopause. Sarcopenic obesity was defined as ASM index < 5.7 kg/m² combined with PBF ≥ 35%. ASM and PBF were measured by bioelectrical impedance analysis with an InBody 720 device. Obesity, defined by BMI or waist circumference, was used for the sensitivity analyses. Associations were analyzed using generalized estimating equations. <b>Results:</b> Participants had a mean age and BMI of 42.2 years (SD 3.0) and 22.1 kg/m² (SD 2.9), respectively; 16.1% had high body fat, and 15.6% had low muscle mass. Increased age was associated with higher odds of sarcopenic obesity (OR 1.07, 95% CI: 1.03-1.10). Compared to pre-menopause, late transition (OR 1.49, 95% CI: 1.17-1.89) and post-menopause (OR 1.67, 95% CI: 1.26-2.23) were significantly associated with sarcopenic obesity, independent of confounders. Similar trends were observed using waist circumference-based definitions. No significant associations were identified using BMI-based definitions (BMI ≥ 23 kg/m²), although positive trends were observed. <b>Conclusions:</b> In middle-aged Korean women undergoing natural menopause, sarcopenic obesity increased across menopausal stages, becoming significant from the late transition. These unfavorable changes were more evident when using body composition measures, suggesting that BMI alone may underestimate such changes during menopausal transition.