Increasing demands and concerns for the reliable supply of liquid transportation fuels makes it important to find alternative sources to petroleum based fuels. One such alternative is cellulosic biofuels. However, several technical barriers have hindered large-scale, cost-effective manufacturing of cellulosic biofuels, such as the low density of cellulosic feedstocks (causing high transportation and storage costs) and the lack of efficient pretreatment procedures for cellulosic biomass. This paper reports experimental investigations on ultrasonic vibration-assisted (UV-A) pelleting of cellulosic feedstocks. It studies effects of input variables (ultrasonic vibration, moisture content, and particle size) on output variables (pellet density, stability, durability, pelleting force, and yield of biofuel conversion) in UV-A pelleting. Results showed that UV-A pelleting could increase the density of cellulosic feedstocks and the yield of biofuel conversion.