Lactobacillus salivarius SMXD51 was previously isolated from the cecum of a Tunisian poultry and found to produce a bacteriocin-like substance highly active against the foodborne pathogen Campylobacter jejuni. The aim of this study was to examine some probiotic properties of the strain: acid and bile tolerance, capacity of adhesion, stimulation of immune defences (IL-6, IL-8, IL-10 and β-defensin 2), and modulation of the barrier integrity. The results showed that L. salivarius SMXD51 can tolerate gastrointestinal conditions (acid and bile), adhere to intestinal cells and stimulate the immune system. The bacterium strengthened the intestinal barrier functions through the increase of the transepithelial electrical resistance (TEER) and reinforcement of the F-actin cytoskeleton. One hour pretreatment with L. salivarius SMXD51 protected against Pseudomonas aeruginosa PAO1-induced decrease of TEER and damage of the F-actin cytoskeleton. Our results highlight that L. salivarius SMXD51 fulfils the principle requirements of an efficient probiotic and may be seen as a reliable candidate for further validation studies in chicken.