Through purposive atomic transmutation and extensive density functional calculations, we design and predict a novel zigzag-shaped Cd2C monolayer exhibiting distinguished structure and properties. The zigzag-shape structure, buckled with two adjacent rows of atoms shifted oppositely with respect to the plane, is formed by tetracoordinate carbon and bicoordinate cadmium. The unique structure topology and resulting electronic hybridizations render the Cd2C monolayer with robust stability and distinctive electronic properties: it is a natural 2D semiconductor with high and anisotropic acoustic-phonon-limited carrier mobilities (∼103–105 cm2 V−1s−1); its fundamental bandgap is moderate ∼1.7 eV and meanwhile, it can be flexibly tuned in a large range of more than 1 eV by external strains. Additionally, as the lowest-energy structure of 2D space, the monolayer exhibits excellent thermal and kinetic stabilities. These outstanding properties indicate that the Cd2C monolayer is a promising nanomaterial for future electronic applications.