KRAS, one of the most frequently mutated oncogenes in cancer, has long posed a formidable therapeutic challenge due to the difficulty of directly inhibiting its activity. A major breakthrough emerged with the development of covalent, allele-specific in-hibitors targeting KRASG12C, such as sotorasib. However, the clinical utility of these inhibitors is frequently limited by the rapid development of acquired resistance. Targeted protein degradation (TPD) has emerged as an effective approach with the potential to overcome drug resistance, but it has been mostly restricted to large-size PROTACs. In this study, we present the first small-molecule KRASG12C degrader, DJX-A-KM, designed by integrating a simple acrylamide warhead into the hydrophilic moiety of the MRTX849 scaffold. DJX-A-KM induces rapid, robust, and sustained degradation of KRASG12C in both cellular and animal models (DC50: 2 nM; Dmax: 98%; 60h durability), demonstrating superior pharmaceutical properties to PROTACs. Mechanistic investigations revealed that degradation is mediated by the ubiquitin-proteasome system, facilitated by covalent engagement with a new E3 ligase, FBXO28, at cysteine 98 through the acrylamide warhead. Antiproliferation assays demonstrated its potent in-hibitory effects across multiple KRASG12C-mutant cancer models, with in vivo studies confirming significant tumor growth sup-pression mediated by targeted KRASG12C degradation. Notably, this chemical strategy extends beyond KRASG12C, offering a blueprint for developing pan-KRAS degraders against a broader spectrum of KRAS mutations. To our knowledge, this study reports the first small-molecule degrader that recruits FBXO28 as an E3 ligase, employing a novel dual covalent strategy to achieve the highest targeted degradation of KRASG12C thus far. Additionally, it represents the first small-molecule pan-KRAS degrader and provides a feasible approach for exploring new E3 ligases in targeted protein degradation applications.