Background: This study aimed to explore the correlations of programmed death-1 (PD-1) and CC chemokine ligand 20 (CCL20) with Treg/T helper 17 (Th17) balance in patients with HBV-ACLF. Methods: In this cross-sectional study, 50 patients with HBV-ACLF and 50 cases with chronic hepatitis B (CHB) diagnosed from February 2021 to February 2022 were selected, and another 50 healthy volunteers who received physical examinations in the same period were selected as a control group. The expression levels of PD-1, CCL20, and Treg/Th17 cytokines were detected by Western blotting, immunoturbidimetry, and enzyme-linked immunosorbent assay (ELISA), respectively. The correlations of PD-1 and CCL20 with Treg/Th17 cytokines were explored by Pearson analysis. The predictive values of PD-1, CCL20, and Treg/Th17 cytokines for the prognosis of HBV-ACLF patients were analyzed. Results: The expression levels of PD-1 and CCL20 were higher in the HBV-ACLF group than in the CHB and control groups (P < 0.05). Severe HBV-ACLF patients had higher levels of PD-1 and CCL20 compared with mild and moderate HBV-ACLF patients (P < 0.05). Hepatitis B virus-related acute-on-chronic liver failure patients with poor prognosis had higher levels of PD-1 and CCL20 than those with good prognosis (P < 0.05). The levels of transforming growth factor β (TGF-β), interleukin 10 (IL-10), IL-23, and tumor necrosis factor α (TNF-α) were higher in the HBV-ACLF group than in the CHB and control groups (P < 0.05). The levels of PD-1 and CCL20 in the HBV-ACLF group were positively correlated with those of Treg/Th17 cytokines (TGF-β, IL-10, IL-23, and TNF-α; P < 0.05). The combined detection of PD-1, CCL20, and Treg/Th17 cytokines had higher sensitivity and lower specificity than single detection in predicting the prognosis of HBV-ACLF patients (P < 0.05). Conclusions: The expression levels of PD-1 and CCL20 are higher in HBV-ACLF patients, being correlated with Treg/Th17 balance. The combined detection of PD-1, CCL20, and Treg/Th17 cytokines has a higher value for predicting the prognosis of HBV-ACLF patients.