Squamous cell carcinoma antigen (SCCA) serves as a critical biomarker for cervical cancer, and its early detection is pivotal for enhancing patient outcomes. While traditional methods such as cytological screening and ELISA are established, their high costs and limited sensitivity hinder their widespread adoption for large-scale screening. In this study, we present an MXene-based electrochemical sensor (MX-iEC-SCCA) that markedly improves sensitivity and stability through the superior conductivity and extensive surface functional groups of MXene. The sensor demonstrates a detection range for SCCA from 0.01 pg/mL to 10 ng/mL, with an exceptional detection limit of 0.0036 pg/mL. Reproducibility tests reveal a relative standard deviation (RSD) of 1.51%, with a minimal signal decrease of 0.3% over five weeks, underscoring its stability. In experiments with standard plasma samples, the biosensor demonstrated a robust correlation with target values (R² = 0.9787). Analysis of 15 low-concentration and 16 high-concentration plasma samples yielded highly significant t-test results (p = 3.74E-06 < 0.01). ROC curve analysis further validates the sensor’s efficacy, with an AUC of 0.982, specificity of 0.933, and sensitivity of 0.866. These findings highlight the remarkable reliability and potential of MX-iEC-SCCA for SCCA detection, positioning it as a precise and efficient tool for the early diagnosis of cervical cancer and other malignancies.