Flow rates of fuel are a major control variable in the engines of airborne vehicles. Accuracy in flow rate measurements became a mandatory requirement for the testing and reliable operation of those engines. Flow rate measurement is also essential in food industries, automotive industries, and chemical industries. Flow rate measurement using ultrasonic transducers is an appropriate choice because of its unique properties when they are in contact with the gases and water medium, as well as larger diameter pipelines. Estimating the echo signal of the ultrasonic flowmeter is a challenging task; however, the processing tasks for real-time performance are mandatory for improving accuracy in flow rate measurements. This article reviews the improvement in the accuracy of flow rate measurements of liquids and gases incorporating the modern technological trends with the support of field programmable gate arrays, digital signal processors, other advanced processors, and deep learning approaches. The review also elaborates on the reduction of uncertainty in single path and multi-path ultrasonic flowmeters. Finally, future research prospects are put forward for developing low cost, reliable, and accurate ultrasonic flowmeters for extensive categories of industrial applications.