This study aimed to synthesize nanocellulose (NC) from sugarcane bagasse (SCB) and pineapple crown leaves (PCLs) with the use of the DES-ultrasonication technique. The Box Behenken design (BBD) was used as a design of experiment to explain the effects of parameters on the NC yield. The independent variables varied in this study were reaction temperature (80, 95, 110 °C), time (2, 4, and 6 h), and DES 2 ratio (1:1, 2:1, 3:1). A high yield of NCs was obtained from SCB and PCLs through a DES- ultrasonication process. The maximum yield of 76.91 % was obtained at the reaction temperature, reaction time, and DES ratio of 95 °C, 4 h, and 2:1 respectively for SCB-derived NC. In the case of PCLs, the maximum yield of NC of 69 % resulted from the reaction temperature, reaction time, and DES ratio of 80 °C, 4 h, and 3:1. The yield for both raw materials differed due to the structural variations. NCs obtained from SCB and PCLs exhibited a higher crystallinity index of about 58.10 and 62.07 %, slightly higher than reported studies. SEM images showed the rod-like structures of synthesized NCs. The thermal stability of both the synthesized NCs increased compared to raw materials. Hence, due to their high thermal stability and crystallinity, the synthesized NCs can be suitable for reinforcement polymer composite applications.