Wastewater treatment is shifting from simply removing pollutants to recovering valuable resources. Although membrane and bioelectrochemical technologies are promising tools for this transition, they typically operate independently and rely heavily on external power, limiting their scalability. Here we develop an energy-neutral system that couples electrically assisted forward osmosis (eFO) with a microbial desalination cell (MDC) to autonomously extract nutrients and water recovery from wastewater. Bioelectricity generated from organic oxidation in the MDC (>7.0 mW) directly powers the eFO module (<1.0 mW). This internal energy transfer drives magnesium ion migration to trigger struvite precipitation, boosting nutrient recovery by 184% and water flux by 57% compared to standalone operations. Using a hybrid model to optimize these complex dynamics, our closed-loop design sustains ideal concentration gradients and improves total desalination efficiency by 45%. By eliminating the need for external grids, this self-powered framework offers a practical and scalable blueprint for zero-energy wastewater refineries.