Dogs can develop chronic inflammatory diseases that induce progressive tissue damage and illness. Delphinidin is a component of maqui (Aristotelia chilensis) and has anti-inflammatory and antioxidant effects. This study evaluated the immunomodulatory effects of delphinidin chloride (DC) and delphinidin-3-glucoside (D3G) on neutrophils and peripheral blood mononuclear cells (PBMCs) in dogs. Leukocytes were isolated from 20 clinically healthy dogs and treated with DC and D3G at concentrations of 50, 100, and 150 µM. The cells were then stimulated with lipopolysaccharide (LPS), platelet-activating factor (PAF), or phorbol 12-myristate 13-acetate (PMA) to evaluate cell viability, reactive oxygen species (ROS) production, neutrophil extracellular trap (NET) formation, phagocytosis, chemotaxis, matrix metalloproteinase 9 (MMP-9) activity, and cytokine production. The results showed that both compounds preserved cell viability, significantly reducing ROS production and NET formation. DC significantly increased chemotaxis and D3G significantly reduced MMP-9 activity. Both compounds reduced the secretion of interleukin (IL) 1β (IL-1β) and tumor necrosis factor α (TNF-α) in neutrophils. In PBMCs, they decreased the production of IL-4 and IL-6 and modulated the production of interferon γ (IFN)-γ. In conclusion, delphinidin exerts selective anti-inflammatory activities in canine leukocytes, promoting inflammation resolution, suggesting its potential role as a nutraceutical for managing inflammatory pathologies in dogs.