A locking grommet system includes threaded-tube, locking-collar, and cover-plate. Locking grommet system is configured to penetrate a wall such that a user may pass objects through the wall penetration. Threaded-tube includes first-edge, second-edge, inside-surface, and outside-surface. Outside-surface includes male threads, and first-edge includes a lip. The lip is configured to contact a first-wall-surface. Cover plate is insertable into first-edge and configured to decrease the size of the opening of threaded-tube. Threaded-tube includes at least two tabs on inside-surface configured to provide user with a mechanism to rotate the threaded-tube in relation to the locking-collar. Locking-collar is cylindrical and includes collar-body and locking-tabs. The collar body includes front-edge, rear-edge, interior-surface, and exterior-surface. Interior-surface includes female threads configured to couple with male-threads of threaded-tube, and locking-tabs are configured to rotate outwardly from retracted position to extended position to contact a second-wall-surface.