Microorganisms have broad applications in disease treatment, bioremediation, and gut microbiota modulation. However, their survival rate and targeted delivery efficiency in complex environments, such as the gastrointestinal tract, remain major practical challenges. Metal-tannic acid complexes exhibit excellent biocompatibility, tunable degradability, and surface functionalization potential, making them suitable for constructing protective coatings on microbial surfaces. This chapter describes a robust and straightforward protocol for fabricating a conformal metal-phenolic network (MPN) coating on microorganisms via the sequential self-assembly of iron ions (Fe3+) and tannic acid. The method includes detailed procedures for material preparation, the rapid coating process, comprehensive characterization, and functional assessment. This simple, versatile, and efficient strategy offers a promising platform for advancing probiotic encapsulation and engineered microbial therapeutics.