The partial substitution of chemical fertilizer with manure is increasingly recognized as a promising strategy for achieving sustainable agriculture. This study aimed to investigate the effects of different manure substitution ratios on grain yield and its components, plant nitrogen accumulation, grain appearance quality, carotenoid content, and pasting properties. A two-year field experiment (2020-2021) was conducted with six treatments: no fertilizer application (CK), chemical fertilizer (NPK), 25% substitution of chemical nitrogen with manure (25% M), 50% substitution (50% M), 75% substitution (75% M), and 100% substitution (100% M). Results indicated that plant nitrogen accumulation was highest with 25% M and decreased as the proportion of manure substitution increased, which subsequently affected grain yield and quality. In 2020, 25% M increased plant nitrogen accumulation by 9.6% compared to NPK. In 2021, 25% M produced the highest values for plant nitrogen accumulation, aboveground biomass, grain yield, and grain number per ear, with increases of 6.1%, 12.0%, 15.4%, and 12.0%, respectively, compared to NPK. Grain appearance quality, pasting properties, and carotenoid content were significantly influenced by the 50% M treatment. Compared to NPK, 50% M increased the a* parameter (indicating red or green coloration) by 6%, CCI (indicating orange coloration) by 6%, and final viscosity by 7.8%. Additionally, amylopectin, total starch, lutein, zeaxanthin, and yellow pigment contents increased by 7.4%, 4.3%, 20.68%, 17.4%, and 2.8%, respectively, under 50% M compared to NPK. However, 100% M significantly reduced plant nitrogen accumulation, biomass, grain number per ear, and grain yield relative to NPK, and had no positive effects on lutein and zeaxanthin contents. Pearson correlation analyses revealed that plant nitrogen accumulation was negatively related to grain weight, amylose content, and setback viscosity in 2020 and 2021. A negative correlation was also observed between plant nitrogen accumulation and total starch content, protein content, peak viscosity, and yellow pigment content in 2021, while a positive correlation was found between plant nitrogen accumulation and trough viscosity. In conclusion, under a total nitrogen application rate of 120 kg hm-2, substituting 25%-50% of chemical nitrogen with manure enhanced plant nitrogen accumulation, which in turn improved yield, grain appearance quality, pasting properties, and carotenoid content in foxtail millet grains.