In various examples, in-path object detection for autonomous and semi-autonomous systems and applications is described herein. For instance, systems and methods may use sensor data, such as inertial measurement sensor data, to generate or determine a lane that is associated with a vehicle. In some examples, the lane is generated or determined by determining a curvature of a path that the vehicle is navigating and then adding distance boundaries to both sides of the path. The systems and methods may then use sensor data, such as RADAR data and/or LiDAR data, to determine one or more locations of one or more objects with respect to the vehicle. Using the geometry of the lane and the location(s) of the object(s), the systems and methods may then determine whether the object(s) is located along the path of the vehicle.