<p>Efficient removal and stabilization of Ni²⁺ in wastewater remain challenging, particularly under elevated loadings and variable operating conditions. Here, a hydrogel-based adsorption–microbially induced calcium carbonate precipitation (MICP) system was constructed using immobilized composite microbial beads (IMBs) integrating a three-strain consortium with embedded adsorbents. The consortium achieved 50.1% Ni²⁺ removal at 20 mg·L⁻¹ within 24 h, clearly outperforming a single-strain MICP system. Under optimized conditions (pH 9.0, 40 °C, 150 rpm, 24 h), the IMB system achieved 99.2%, 99.0%, and 98.7% Ni²⁺ removal at 20, 100, and 200 mg·L⁻¹, Structural analyses revealed Ni immobilization via coordinated surface binding coupled with co-precipitation and partial lattice incorporation into CaCO₃. The system retained 85–95% removal efficiency after five regeneration cycles, demonstrating strong durability. This integrated adsorption–mineralization strategy enables rapid capture and stable mineral fixation of Ni²⁺, offering a robust and promising for scale-up for advanced heavy-metal wastewater treatment.</p>