Aberrant methylation of some genes can serve as promising biomarkers in hepatocellular carcinoma (HCC). This study aimed to investigate the diagnostic and prognostic value of plasma SGIP1 methylation in HCC. The study included a total of 269 subjects, of which 129 were with HCC, 45 with liver cirrhosis (LC), 45 with chronic hepatitis B (CHB), and 50 were healthy controls (HCs). The aberrant methylation was detected by quantitative methylation-specific polymerase chain reaction (qMSP). The area under the curve (AUC) was 0.872 in distinguishing HCC from HCs, with a sensitivity of 85.3% and a specificity of 88%. The AUC was 0.728, when it distinguished HCC from CHB, with a sensitivity of 43.4% and a specificity of 97.8%. The AUC was 0.728 in distinguishing HCC from LC, with a sensitivity of 43.4% and a specificity of 97.8%. Elevated levels of SGIP1 methylation in HCC patients showed poorer overall survival (OS), progression-free survival (PFS), and metastasis-free survival (MFS) than those with low levels (Kaplan-Meier method and the log-rank test, p< 0.05). SGIP1 methylation in different study groups demonstrated different sensitivities. SGIP1 methylation detection in the plasma may serve as a non-invasive diagnostic and prognostic biomarker for HCC.