The compaction and hardening of red soil led to an imbalance of water and air, thereby affecting the improvement of crop yield and quality. Micro-nano bubble water and biochar had the potential to improve the soil's water and gas environment, but their synergistic effects were unclear. This study focused on greenhouse cucumbers and employed a two-factor comparative experimental design, combining in-situ monitoring, correlation analysis, and principal component analysis to explore the coupling effects of dissolved oxygen concentrations in micro-nano bubble water (4–5, 9–10, 14–15 mg/L) and biochar application rates (20, 40, 60 t/hm²) in 2024 and 2025. The coupling of micro-nano bubble water and biochar significantly increased the average soil moisture, yield, water productivity (WP), and these indicators improve with the increased in dissolved oxygen concentration and biochar application amount, while water consumption (ET) decreased. A higher biochar application combined with an appropriate dissolved oxygen concentration reduced ET. The fruit quality response showed a nonlinear change, and an appropriate combination was beneficial for promoting sugar accumulation and reducing total acid content, thereby increasing the sugar-acid ratio. Yield was extremely significantly positively correlated with soil moisture and WP. The optimal "oxygen-biochar" management scheme was the combination of dissolved oxygen (9∼10 mg/L or 14∼15 mg/L) and biochar (60 t/hm²), which effectively improved the soil water-air environment, enhanced water use efficiency, and achieves increased in both yield and quality. The research findings had reference value for increasing crop yield and quality in compacted acidic red soil areas.