A data storage device and method for reliable watermarking are provided. In one embodiment, a data storage device is provided comprising a memory and a controller. The controller is configured to determine whether a watermarking operation to be performed on the data is to be performed by the controller or by the memory; in response to determining that the watermarking operation is to be performed by the controller, performing the watermarking operation; and in response to determining that the watermarking operation is to be performed by the memory, instruct the memory to perform the watermarking operation. Other embodiments are provided.