Most fungal pathogens secrete effector proteins inside host cells to circumvent host immune responses, thereby promoting pathogen virulence. One such fungal pathogen is Fusarium graminearum, which causes Fusarium Head Blight (FHB) disease on wheat and barley. Recent transcriptomic analyses revealed that F. graminearum likely secretes nearly six hundred effector proteins during the early phases of the infection process, some of which are annotated as proteases. However, the function of F. graminearum effector proteases in plant pathogenesis remains unknown. Here, we identified a F. graminearum endopeptidase, FgTPP1 (FGSG_11164), that is highly upregulated during early stages of wheat spikelet infection. To elucidate the potential role of FgTPP1 in F. graminearum virulence, we generated FgTPP1 deletion mutants (ΔFgTPP1) and performed FHB virulence assays. While the ΔFgTPP1 mutant was able to colonize the inoculated spikelet, the disease symptoms were consistently reduced when compared to wild-type F. graminearum strain PH-1. To further elucidate the potential mechanisms involved, we transiently expressed FgTPP1 in Nicotiana benthamiana using agroinfiltration. Our analyses revealed that FgTPP1 localizes to the chloroplast stroma and suppresses both chitin-dependent reactive oxygen species (ROS) production as well as NLR-mediated defense responses. Our results provide new insights into the functions of a F. graminearum effector protease in plant pathogenesis.