•A MXene catalyzed Faraday cage-type ECL immunosensor for GM crops was developed.•MXene catalyzes the ECL reaction of PTCA, enhancing ECL intensity about 4 times.•Sensitivity is doubly improved by Faraday cage-type sensor mode and MXene catalysis.•Cry1Ab is detected in the range of 0.005 ∼ 100 ng mL−1 with a LOD 0.001 ng mL−1.•GM maize MON810 is detected in the range of 0.005 % ∼ 2.0 % with a LOD 0.001 %. Herein, a MXene catalyzed Faraday cage-type electrochemiluminescence (ECL) immunosensor was developed for the detection of transgenic component Cry1Ab protein in genetically modified (GM) crops. The capture unit Fe3O4-Ab1 is Fe3O4 nanoparticles coated by capture antibody Ab1, while the signal unit MXene-PTCA-Ab2 is two-dimensional conductive material MXene with ECL labels 3,4,9,10-perylenetetracarboxylic acid (PTCA) and recognition antibody Ab2 simultaneously immobilized. In presence of the target Cry1Ab, the Faraday cage-type electrochemical immunosensor could be constructed by forming the capture unit-Cry1Ab-signal unit immunocomplex. In addition to the inherently high sensitivity brought by the Faraday cage-type sensor construction mode, MXene in the signal unit catalyzes the reduction of dissolved O2 to form reactive oxygen species which could accelerate the ECL reaction, resulting in a secondary ECL enhancement of PTCA and ensuing higher detection sensitivity. Under the optimized experimental conditions, Cry1Ab protein and GM maize MON810 could be quantitatively detected in the range of 0.005 ∼ 100 ng mL−1 and 0.005 % ∼ 2.0 %, with limit of detections (LODs) 0.001 ng mL−1 and 0.001 % respectively. Selectivity, stability, repeatability, precision, and accuracy are all satisfactory. Detection of actual samples is successful, showing its application prospect in the field of agriculture and food safety.