It is crucial in dairy farming that a smooth transition from prepartum to postpartum period for optimal dairy cow health and performance. Whether rumen-protected niacin supplementation could be a useful additive was controversial. The aim of this study was to investigate the effects of rumen-protected niacin on dry matter intake, milk production, feed digestibility, and the fecal bacterial community in postpartum cows. We found that dry matter intake, concentrations of intake-related hormones neuropeptide Y and orexin-A, and milk production of cows were significantly higher in cows with 20 g/d rumen-protected niacin supplement compared with the control while no impact in apparent total tract digestibility of nutrient and fecal bacterial community during the postpartum period. This work supports the further widespread use of rumen-protected niacin in multiparous Holstein dairy cows.