Abstract: Anion antisite defects in monolayer Transition Metal Dichalcogenide (TMD) systems are here identified as two-dimen-sional solid-state defect qubits. The proposed antisites in these TMDs host paramagnetic triplet ground states with flexible level splitting. A viable transition loop between the triplet and singlet defect states is demonstrated, including optical excitations/relaxations and nonradiative decay paths for the antisites as qubits. A complete set of qubit operational processes, including initialization, manipulation, and readout, is delineated.