To achieve optimal blood pressure control in continuous ambulatory peritoneal dialysis (CAPD) patients, identifying methods of volume assessment with the strongest correlation with blood pressure is essential. In this cross-sectional study, 52 CAPD patients were assigned to automated office blood pressure (AOBP) measurement, assessment of pedal pitting edema, bioimpedance analysis (BIA), and inferior vena cava collapsibility index (IVCCI%) measurement. Data were analyzed using STATA ver.17, and the significance level was p < 0.05. Fifty-two patients were divided based on their AOBP readings. 29 (55.8%) of patients had uncontrolled AOBP. Overhydration (OH) and the grade of pitting edema were significantly higher in the uncontrolled AOBP group. OH was identified as the best variable for predicting blood pressure (p ≤ 0.001) and detecting uncontrolled blood pressure (AUC = 0.832) using multivariate linear regression and ROC analysis, respectively. BIA-derived OH was the best variable for predicting systolic and diastolic AOBP, outperforming IVCCI% and pitting edema.