This work presents the temperature-dependent analysis of heterojunction-free gallium nitride (GaN) FinFET through optimization of controlling gate parameters and dielectric materials. The temperature-dependent performance evaluation presents in terms of the transfer characteristic, transconductance, subthreshold swing (SS), and drain-induced barrier lowering (DIBL). Further, parametric assessment has been performed by gate length (Lg) and oxide thickness (tox) variation for optimization. Moreover, the different gate dielectric materials (Al2O3, ZrO2, and Si3N4) have also been used for different temperatures to optimize suitable gate dielectric material for improved performance of the device. Thus, GAN FinFET can be considered a promising component in high temperatures in IC and RF amplifiers.