Background/Objectives: Endothelial dysfunction plays a central role in the development of cardiovascular diseases. β-Casomorphin-7 (BCM-7), a biologically active peptide generated during the digestion of A1 β-casein, is presumed to contribute to this process; however, its direct effects on endothelial cells have not been previously investigated. Here, we aimed to assess whether BCM-7 treatment induces endothelial cell dysfunction through inflammatory cytokines and reactive oxygen species (ROS). Methods: In our study, we analyzed the effects of BCM-7 (5 µg/mL) in combination with lipopolysaccharide (LPS, 100 ng/mL) on human umbilical vein endothelial cells (HUVECs/TERT2). The cell viability, apoptosis, necrosis, and intracellular reactive oxygen species were measured. Furthermore, proinflammatory cytokines and enzymes involved in the regulation of inflammation were assessed with quantitative real-time PCR. The gene and protein expression of enzymes that regulate inflammation and vascular function, thus maintaining endothelial homeostasis were assessed. Results: BCM-7 enhanced intracellular ROS production p ≤ 0.001, increased the expression of interleukin-6 (IL-6) and interleukin-8 (IL-8) p ≤ 0.001, and was more effective when used in combination with LPS p ≤ 0.001. It decreased the expression of cyclooxygenase-1 (COX-1) p ≤ 0.05, during 4 h of exposure, whereas it increased the expression of cyclooxygenase-2 (COX-2) p ≤ 0.001, lipoxygenase-5 (LOX-5) p ≤ 0.01, and nitric oxide synthase 3 (NOS3) p ≤ 0.001; prostaglandin D2 synthase (PTGDS) (p ≤ 0.05), expression was also increased after short treatment. Conclusions: Our results suggest that BCM-7 may contribute to the development of endothelial dysfunction, especially in the presence of LPS, by enhancing oxidative stress and inflammatory response.