Mesenchymal stromal cells (MSCs) are believed to migrate to injury sites, release chemical attractants, and either recruit local stem cells or modulate the immune system positively. Although MSCs are highly desired for their potential to reduce inflammation and promote tissue regeneration, their limited lifespan restricts their applications. This study presents a simple approach for protecting MSCs with epigallocatechin-3-gallate (EGCG) and magnesium (Mg) based metal-organic framework coatings (E-Mg@MSC). The layer strengthens MSCs resistant to harmful stresses and creates a favorable microenvironment for repair by providing Mg to facilitate MSCs' osteogenic differentiation and using EGCG to neutralize excessive reactive oxygen species (ROS). E-Mg@MSC serves as a treatment for hematopoietic injury induced by ionizing radiation (IR). Coated MSCs exhibit sustained secretion of hematopoietic growth factors and precise homing to radiation-sensitive tissues. In vivo studies show substantial enhancement in hematopoietic system recovery and multi-organ protection. Mechanistic investigations suggest that E-Mg@MSC mitigates IR-induced ROS, cell apoptosis, and ferroptosis, contributing to reduced radiation damage. The system represents a versatile and compelling strategy for cell-surface engineering with functional materials to advance MSCs therapy.