In this paper, we report on a novel, environmentally superior tribomaterial with superlow friction of 100% cellulose nanofiber (CNF) molding. Based on our experimental results, the CNF molding exhibited a superlow friction coefficient of approximately 0.01 under lubrication with a fatty acid: glycerin monooleate (GMO) diluted with poly-alfa-olefine. Attenuated total reflection Fourier-transform infrared spectroscopy and high-resolution frequency-modulation atomic force microscopy analyses demonstrated that superlow friction of the CNF molding was realized by GMO-assisted functionalization of the CNF surface, which effectively promoted the formation of a soft absorption film or soft swollen CNF layer. Our findings indicate that the in-situ functionalization of OH-terminated CNF surfaces during the friction process plays a crucial role in achieving superlow friction.