An approach is provided for device-side probe trajectory anonymization based on negative gapping. The approach involves, for example, collecting a probe trajectory stream from a sensor of a probe device, wherein the probe trajectory stream comprises a time-sequence of location data points representing a sensed movement of the probe device. The approach also involves generating a plurality of subtrajectory streams from the probe trajectory stream. The approach further involves processing the plurality of subtrajectory streams to create a negative gap between the plurality of subtrajectory streams. The approach further involves providing the plurality of subtrajectory streams as an output in place of the probe trajectory.