Context: Rainfed maize in China is essential for global food security. Efforts to develop sustainable pathways for improving rainfed maize yield necessitate a comprehensive understanding of the magnitude and causes of its yield gap. However, isolating and quantifying the multitude of causes behind the yield gap poses a significant challenge. Objective: To assess the contributions of soil fertility and fertilizer to the yield gap, decompose the yield gap, and propose strategies to improve rainfed maize productivity. Methods: We hence established a database of 2021 rainfed maize plantings in the East Loess Plateau of China. Soil fertility was classified into four levels based on the soil fertility index (SFI). Three fertilization treatments were applied: no fertilization control (CT), soil testing and fertilization recommendation (SF), and regular fertilization (RF). The total yield gap (YG-Total) was then decomposed into four components: management yield gap (YG-M), soil fertility yield gap (YG-S), resource yield gap (YG-R), and technology yield gap (YG-T) by combining agronomic approaches with the stochastic frontier analysis. A Structural Equation Model (SEM) was also employed to elucidate the mechanisms for narrowing these gaps. Results: A YG-Total of 3833 kg/ha, 33.32 % of the water-limited potential yield (Yw), was revealed, which was primarily attributed to YG-M (29.79 %), YG-S (27.42 %), and YG-R (24.79 %), with distinct decomposition characteristics across different soil fertility levels and fertilization treatments. Specifically, a one-unit increase in the SFI was associated with an additional yield of 1125 kg/ha. Meanwhile, the rainfed maize yield under SF reached to 9194 kg/ha, and increased to 10,814 kg/ha when efficiency losses were excluded. The SEM analysis revealed three pathways to narrow the yield gaps: addressing the drivers of YG-S and YG-R, enhancing agricultural infrastructures, and regulating the interactions among the components of the YG-Total. Conclusions: By decomposing the yield gap into distinct components (YG-M, YG-S, YG-R, and YG-T), we demonstrate that soil fertility improvement (YG-S) and optimized fertilization (YG-M) are the most critical practices for enhancing productivity, together contributing over 57 % of the closable yield gap, while taking into account tailored regional characteristics is also essential for narrowing the rainfed maize yield gap. Implication: This study provides a systematic framework for quantifying and narrowing yield gaps in rainfed maize systems, offering actionable insights for sustainable intensification in semi-arid and arid regions.