Probiotic feed additives with potential to enhance performance, health, and immunity have gained considerable popularity in commercial broiler production. The study objectives were to measure broiler performance, gut integrity, and splenic immune cell profiles in birds fed one of 2 probiotics at 2 inclusion levels. Nine hundred and sixty Ross 708 broilers (12/ pen) were randomly assigned to no additive control, 0.05 or 0.10% LactoCare (Lactobacillus reuteri), or 0.05 or 0.10% LactoPlan (Lactobacillus plantarum) dietary treatments for 6 wk. On d27, a 20-pen subset was utilized for a fluorescein isothiocyanate dextran (FITC-d) assay, where half of the pens were subject to a 12-h feed restriction (FR) pre-gavage. Serum collected from blood drawn 1-h post-gavage was analyzed for relative fluorescence of FITC-d absorbed across the intestinal barrier as a gut leakiness indicator. On d42, spleens from 8 birds/ treatment were collected for immune cell profile analysis by multicolor flow cytometry. Although performance outcomes were not affected by dietary treatment, FITC-d absorption post-FR was increased 57% in the 0.05% LactoPlan treatment, and was decreased by 12.6% in the 0.05% LactoCare diet, 12% in the 0.10% LactoCare diet, and 22% in the 0.10% LactoPlan diet compared to the control. This indicates a positive impact in barrier integrity maintenance due to 0.05% and 0.10% LactoCare and 0.10% LactoPlan diet following a challenge. Immune cell profiles varied between the two probiotic compositions, with an approximately 50% reduction in splenic innate immune cells (monocyte/macrophage+) in birds fed LactoPlan (P < 0.0001) and greater overall percentages of CD45+ leukocytes and CD3+ T-cells in birds fed 0.10% LactoCare (P < 0.0001). LactoPlan diets shifted splenic T-cell populations in favor of CD8+ cytotoxic T-cells (TC; P= 0.007), while higher inclusions (0.10%) of either probiotic increased the percentage of activated CD4+ helper T-cells (TH; P < 0.0001). These results indicate that compositionally different probiotics had varying effects on the gut permeability and splenic immune cell profiles in broiler chickens, particularly at higher inclusion rates, but observed changes to underlying physiology did not negatively impact performance outcomes. The ability of a probiotic to alter gut permeability and immune cell profile therefore may depend on the compositional complexity of the product as well as inclusion rate.