The power grid CO₂ emission factor is a critical parameter for accurately calculating indirect emissions from the electricity consumption side, serving as a core indicator for precisely quantifying the CO₂ emission pathways at the consumption side. This study explores the temporal and spatial characteristics of the province-level power-grid CO₂ emission factors from 2020 to 2035 and compares them with official-source factors. Moreover, it integrates historical direct-emission data to accurately quantify the importance of indirect emissions from the electricity consumption side. Additionally, it predicts the province-level indirect emissions and emission pathways under different scenarios from 2020 to 2035, quantifying the impacts of power grid CO₂ emission factors with distinct temporal and spatial accuracies on provincial emission pathways. The results indicate that: (1) from 2020 to 2035, the power grid CO₂ emission factors of all provinces are expected to exhibit sustained decreasing trends, and there are disparities between the existing publicly available power-grid CO₂ emission factors and provincial levels in the study. (2) From 2010 to 2020, the indirect emissions from electricity consumption and their proportions in net electricity-importing provinces had gradually increased, with Beijing, Shanghai, and Zhejiang province having the largest proportions. (3) Under Scenarios 1 (constant power-grid CO₂ emission factors on the national level) and 3 (constant power-grid CO₂ emission factors on the provincial level), the indirect emissions from electricity consumption and total emissions of all provinces will be significantly higher than the estimated results in Scenarios 2 (dynamic power-grid CO₂ emission factor on the national level) and 4 (dynamic power-grid CO₂ emission factor on the provincial level). The estimation results of Scenarios 1 and 2 are projected to differ significantly from those of Scenarios 3 and 4. For provinces with large proportions of indirect emissions from electricity consumption, such as Beijing, Shanghai, and Guangdong, selecting power grid CO₂ emission factors with different spatial accuracies is expected to have noticeable impacts on their total emissions, further leading to shifts in their peaking years. The research results can provide a reference for supporting the planning of carbon peaking pathways in various provinces and reducing the uncertainty in indirect emission forecasts.