Fibrotic diseases, which impair tissue function and contribute to organ failure, remain a major clinical challenge with limited treatment options. Mesenchymal stromal cells (MSCs) offer promise for antifibrotic therapy via paracrine signaling, but their clinical efficacy is hindered by poor survival and limited functional activity after transplantation. Here, we present a cell surface engineering strategy that reprograms the antifibrotic function of MSCs by constructing a pseudofibrotic extracellular matrix (ECM) on their surface. Through in situ self-assembly of peptide-modified hyaluronic acid, we generate a nanofiber-based matrix that mimics the dense, disordered architecture of fibrotic ECM. This matrix activates the Piezo1/PI3K-Akt signaling pathway, inducing up-regulation of Mmp13-a key collagen-degrading matrix metalloproteinase-in engineered MSCs. In a rat model of myocardial infarction-associated fibrosis, engineered MSCs exhibit robust antifibrotic activity compared to unmodified MSCs. These findings establish a bioinspired strategy for MSC reprogramming and offer a path toward more effective cell-based therapies for fibrotic disease.