Display omitted •A ratiometric ECL sensor was constructed using luminol as single luminophor.•The ECLanodic/ECLcathodic was independent with the coreactant H2O2 concentrations.•The ratiometric sensor showed superior sensitivity and accuracy than the single-signal sensors.•4. The proposed ECL sensor exhibited high sensitivity for CEA detection with a wide linear range and a low detection limit. Ratiometric electrochemiluminescence (ECL) assays have attracted widespread attentions in biosensing owing to their precise measurements by eliminating the environmental interferences. However, they mostly needed two eligible luminophors, increasing the complexity of the systems and limiting their practical applications. Herein, using luminol as single luminophor, a dual-potential ratiometric ECL strategy was proposed to detect carcinoembryonic antigen (CEA). The luminol exhibited cathodic and anodic emissions on graphene-ionic liquid-platinum (GR-IL-Pt) composites and Ti3C2 MXenes-Au NPs hybrids, respectively. Then, a sandwich ECL sensor was fabricated using GR-IL-Pt composites as matrix to immobilize the primary antibodies of CEA and Ti3C2 MXenes-Au NPs hybrids as platform to load the secondary antibodies. With the presence of CEA, the ratio of anodic ECL to cathodic ECL (ECLanodic/ECLcathodic) increased obviously, realizing sensitive ratiometric detection of CEA. In addition, the ECLanodic/ECLcathodic was independent with the concentrations of H2O2, greatly improving the test reliability. The developed ECL sensor exhibited a sensitive detection toward CEA, performing a wide linearity in the range of 0.1 pg mL−1 - 10 ng mL−1 with a low detection limit of 34.58 fg mL-1 (S/N = 3). Furthermore, this strategy exhibited a good practicality to detect CEA in human serums, providing a promising strategy in ECL bioanalysis.