This paper proposes G-VIDO, a vehicle dynamics, and intermittent Global Navigation Satellite System (GNSS)-aided visual-inertial state estimator, to address the state estimation problem of autonomous vehicle localization (i.e., position and orientation estimation in the global coordinate system) under various GNSS states. A dynamics pre-integration theory is proposed on the basis of a two-degree-of-freedom (DOF) vehicle dynamics model, and dynamics constraints are built in the optimization back-end, considering the unobservable problem of the monocular visual-inertial system under degenerate motions. The proposed highly nonlinear system can be robustly initialized by loosely aligning the monocular structure from motion (SfM) results, pre-integrated IMU measurements, and vehicle motion information. GNSS is used for reference frame transformation and constraint construction in the sliding window. The cumulative error can be corrected with the aid of GNSS, and the vehicle’s position in the global coordinate system can be determined. A GNSS anomaly detection algorithm is proposed to improve the system robustness under intermittent GNSS. Experiments have shown that G-VIDO can provide real-time, robust, and seamless localization in multiple GNSS states, with an RMSE of less than 30 cm (with GNSS). Moreover, we proved that the initialization and local odometry modules in G-VIDO outperform several state-of-the-art VIO systems and our preliminary work VINS-Vehicle.