Although Blufensins (Bln) have important functions in the response of plants to biotic stress the precise functioning of Bln in wheat remains largely unknown. Here we isolated a Bln gene (TaBln4) from Suwon 11 infected by Puccinia striiformis f. sp. tritici (Pst). Expression of TaBln4 increased in host plants at the early stage of infection with a virulent Pst race (CYR31) but was unchanged in response to infection by an avirulent race (CYR23). Transcription levels of TaBln4 were also regulated by hormone and abiotic stresses. Expression of TaBln4 in tobacco leaves suppressed Bax-induced programmed cell death. Knockdown of TaBln4 by virus-induced gene silencing inhibited colonization of race CYR31 by increasing the accumulation of H₂O₂ and formation of hypersensitive responses (HR). Transient overexpression of TaBln4 by a transient overexpression system (BSMV-VOX) increased the susceptibility of wheat to CYR31. Results from bimolecular fluorescence complementation and pull-down assays demonstrated that TaBLN4 interacted with calmodulin. Taken together, our results suggest that TaBln4 negatively regulates resistance in wheat to Pst in a reactive oxygen species (ROS)- and HR-dependent manner.