This study evaluated whether sarcopenic obesity is closely associated with muscle quality using abdominal computed tomography. This cross-sectional study included 13,612 participants who underwent abdominal computed tomography. The cross-sectional area of the skeletal muscle was measured at the L3 level (total abdominal muscle area [TAMA]) and segmented into normal attenuation muscle area (NAMA, +30 to +150 Hounsfield units), low attenuation muscle area (-29 to +29 Hounsfield units), and intramuscular adipose tissue (-190 to -30 Hounsfield units). The NAMA/TAMA index was calculated by dividing NAMA by TAMA and multiplying by 100, and the lowest quartile of NAMA/TAMA index was defined as myosteatosis (<73.56 in men and <66.97 in women). Sarcopenia was defined using BMI-adjusted appendicular skeletal muscle mass. The prevalence of myosteatosis was found to be significantly higher in participants with sarcopenic obesity (17.9% vs. 54.2%, p < 0.001) than the control group without sarcopenia or obesity. Compared with the control group, the odds ratio (95% CI) for having myosteatosis was 3.70 (2.87-4.76) for participants with sarcopenic obesity after adjusting for age, sex, smoking, drinking, exercise, hypertension, diabetes, low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein. Sarcopenic obesity is significantly associated with myosteatosis, which is representative of poor muscle quality.