Aims: The purposes of this study were (1) to compare body composition, physical function, and quality of life (QOL) between patients after coronary artery bypass grafting (CABG) with and without chronic kidney disease (CKD) and (2) to analyze the factors associated with physical function and QOL domains in these patients. Methods: Thirty male post-CABG patients with CKD and 30 matched controls were recruited. All subjects underwent dual-energy X-ray absorptiometry for body composition evaluation. Physical function tests included the grip strength test, 30-second chair stand test (30CST), and 6-min walk test (6MWT). Physical activity and QOL were assessed using the long form of the International Physical Activity Questionnaire and the World Health Organization Quality of Life Instrument (WHOQOL)-BREF, respectively. Results: Post-CABG patients with CKD exhibited a lower arm lean mass and higher percent leg fat mass than those without CKD (p < 0.05). The patients with CKD also had lower 30CST scores, 6MWT distances, and QOL domain of social relationships scores than those without CKD after adjusting for covariates (p < 0.05). If NYHA class was considered in the model, NYHA class became the most important factor associated with 6MWT distances (β = -0.647, p < 0.001) and the QOL domains of psychological health (β = -0.285, p = 0.027) and environment (β = -0.406, p = 0.001). Conclusion: Post-CABG patients with CKD had worse body composition, physical function, and QOL than those without CKD, and this might be associated with a worse NYHA class.