Abstract For effective triboelectric nanogenerator, it remains a major challenge to improve the intrinsic electron-donating properties of positive materials. we report a positive triboelectric nanocomposite material based on chitin, a biopolymer, embedded in a waterborne polyurethane matrix to improve the output performance, sustainability, and robustness of triboelectric nanogenerators (TENGs). This nanocomposite can increase the output performance via electron donating control through the deacetylation of chitin nanofibers. For the deacetylation of chitin, the exposed amine group can be an attractive electron donor combined with polyurethane, resulting in a higher output characteristic (210 V and 3.2 μA/cm2), as confirmed by Kelvin probe force microscopy measurements. Moreover, this nanocomposite film showed good sustainability (V/V0 = 85%) in a humid environment (85 RH%) owing to its hydrogen bonding with water molecules. The hybridized film exhibited excellent robustness (100,000 cycles of bending test, long-term stability test over 10,000 s) in two types of harsh mechanical environments. This flexible, robust TENG with a nanocomposite film can serve as a self-powered motion sensor for monitoring various human motions, such as contact pressure and sliding speed. Combined with a homemade sodium-ion potentiometric sensor, stable operation of the dehydration monitoring system was successfully demonstrated under sweating conditions. For effective triboelectric nanogenerator, it remains a major challenge to improve the intrinsic electron-donating properties of positive materials. we report a positive triboelectric nanocomposite material based on chitin, a biopolymer, embedded in a waterborne polyurethane matrix to improve the output performance, sustainability, and robustness of triboelectric nanogenerators (TENGs). This nanocomposite can increase the output performance via electron donating control through the deacetylation of chitin nanofibers. For the deacetylation of chitin, the exposed amine group can be an attractive electron donor combined with polyurethane, resulting in a higher output characteristic (210 V and 3.2 μA/cm2), as confirmed by Kelvin probe force microscopy measurements. Moreover, this nanocomposite film showed good sustainability (V/V0 = 85%) in a humid environment (85 RH%) owing to its hydrogen bonding with water molecules. The hybridized film exhibited excellent robustness (100,000 cycles of bending test, long-term stability test over 10,000 s) in two types of harsh mechanical environments. This flexible, robust TENG with a nanocomposite film can serve as a self-powered motion sensor for monitoring various human motions, such as contact pressure and sliding speed. Combined with a homemade sodium-ion potentiometric sensor, stable operation of the dehydration monitoring system was successfully demonstrated under sweating conditions.