Purpose. Genetic engineering of mesenchymal stromal cells (MSCs) using viral vectors has emerged as a promising approach to enhance the efficacy of anti-angiogenic gene therapies. Umbilical cord-derived MSCs are an attractive cell source due to their easy accessibility and potential for genetic modification. Adeno-associated viruses (AAVs) have been utilized in clinical settings to deliver therapeutic genes due to its characteristic of transient integration into the genome. In this study, we investigated the efficacy of using recombinant AAV-engineered umbilical cord-derived MSCs overexpressing anti-angiogenic factor, hsFlt-1 (MSCs.hsFlt1). Methods. The plasmid containing the hsFlt-1 gene was cloned into the AAV2 target backbone and validated using Sanger sequencing. The transduction process was studied to determine the optimal conditions, including the effect of MOI, media serum percentage, and attachment of MSCs, to achieve higher transduction efficiency. The functionality of MSCs.hsFtl1 was analyzed using qPCR, ELISA, and tube formation assays. Results. MSCs.hsFtl1 transduced at an MOI of 1 x 106 demonstrated high transduction efficiency and exhibited robust gene and protein expression of hsFlt-1. The results revealed significant inhibition of growth in human umbilical vein endothelial cells (HUVECs) using a remarkably low dose of MSCs.hsFlt1 at 12.3 ng/mL. This observed anti-angiogenic effect was comparable to the clinically used Bevacizumab. Conclusions. The anti-angiogenic potential of MSCs.hsFlt1 effectively demonstrated in this study suggests their promising utility for targeted anti-angiogenic gene therapy approaches.