Selenium, in the form of selenoproteins, plays a pivotal role in anti-inflammatory processes and antioxidant defense system. The aim of this study was to examine the effects of selenium on lipopolysaccharide (LPS)-induced inflammatory responses in bovine mammary epithelial cells (bMEC) and to investigate the potential mechanism. bMEC viability was measured by MTT assay. TNF-α, IL-1β, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) messenger RNA (mRNA) expressions were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The activation of nuclear factor-kappa B (NF-κB) was determined by Western blotting. The results showed that the mRNA expressions of these inflammatory factors were significantly inhibited by selenium in a dose-dependent manner. At protein levels, Western blot analysis demonstrated that selenium dose-dependently decreased NF-κB p65 translocating from the cytoplasm to the nucleus. Taken together, these results suggest that the anti-inflammatory property of selenium in LPS-stimulated primary bMEC may be attributed to the downregulation of NF-κB activation.