The fast detection of obstacles is the key technology for the navigation, obstacle avoidance, and trajectory tracking of mobile robots. Most sensors have problems such as distance blind zone and abnormal scale, and the existing algorithms are generally limited by complex calculation, making it difficult to meet real-time requirements. This paper proposes a new method of rapid obstacle detection and localization for mobile robots based on the difference of inverse perspective mapping. The method takes the level ground as the reference plane to perform inverse perspective transformation on the images captured by the adjacent view cameras in the around view monitoring system mounted on the mobile robots, and obtains the inverse perspective mapping difference by image difference. In the images, the point with zero pixel value is located on the reference plane; otherwise it is outside the plane. After thresholding and filtering operation, the method can be used to distinguish targets not on the reference plane, so as to realize the fast detection of obstacles. Besides, obstacles can be located accurately on the basis of the inverse projection mapping difference through the transformation from the pixel coordinate system to the coordinate system of the robot. Different types, sizes, and distances of obstacles within 5 m were tested. The average detection accuracy was 97.3%, the average detection time per frame was 46 ms, and the average localization error was 1.1%. The experimental results show that the proposed method can quickly and effectively detect and locate the dynamic and static obstacles near the mobile robot.