Amid escalating global challenges to food security and climate resilience, dryland agriculture must concurrently enhance crop productivity and mitigate greenhouse gas emissions. Straw mulching and nitrogen (N) fertilization are widely adopted agronomic practices that influence soil biogeochemical processes and agroecosystem-scale emissions. However, the mechanistic basis by which their interaction regulates ecological functions in dryland wheat systems, particularly through modulation of soil microbial communities, remains poorly understood. To bridge this gap, we conducted a four-year field experiment (2021-2024) in a rainfed winter wheat system on the Loess Plateau of central Gansu Province, China. A randomized two-factorial design-comprising straw mulching (with: CTS vs. Without: CT) and graded N fertilizer rates (0, 55: LN, 110: MN, and 220: HN kg N ha-1)-was employed to quantify treatment effects on soil physicochemical properties, microbial community composition and diversity, nitrous oxide (N2O) flux dynamics, and grain yield. Results revealed robust synergistic interactions between straw mulching and moderate N application (CTSMN): this integrated strategy increased wheat yield by 6.56-29.61% relative to other treatments, while simultaneously reducing cumulative N2O emissions and lowering emission intensity to levels statistically indistinguishable from the unfertilized, non-mulched control. Mechanistically, the combined treatment improved soil structural stability and nutrient retention, shifted nitrogen speciation toward ammonium dominance (suppressing nitrification), and enhanced soil organic carbon and total nitrogen stocks-thereby strengthening long-term C and N sequestration potential. Microbial profiling identified straw mulching as the dominant factor shaping community succession. Co-occurrence network analysis further revealed that bacteria constitute the topological backbone of soil microbial interactions. Under straw mulching, the bacterial network was highly integrated and centered on Bacillus as the keystone species governing network structure and stability, alongside the enrichment of Gaiella and the saprotrophic fungus Coprinopsis. Structural equation modeling further demonstrated that N fertilization exerted a direct positive effect on N2O emissions-mediated primarily by soil acidification and elevated nitrate reductase activity. In contrast, straw mulching indirectly promoted yield gains by ameliorating soil physical conditions, thereby fostering the functional activity of beneficial microbes. Collectively, these findings clarify how coordinated carbon (via straw) and nitrogen inputs regulate soil-microbe-plant feedbacks, offering a mechanistic framework and an evidence-based management protocol for advancing climate-smart, high-yielding dryland wheat production.