Campylobacter jejuni, a zoonotic bacterial pathogen with worldwide distribution, infects about 400 million humans in the world annually. In order to reduce C. Jejuni colonization in the gastrointestinal tracts of broilers and make chickens less susceptible to colonization, four commercial products based on organic acid, probiotics, and medicinal plants were used. In this experiment, 210 one-day-old male broiler chicks (Ross 308) were assigned to 7 treatment groups randomly with 3 replications and 10 birds in each pen. Birds were challenged on day 21 by 1 mL of 6 × 107 CFU/mL C. Jejuni live suspension and samples were collected on days 28 and 42. The immune system's efficiency was evaluated by lymphoid organ development assessment and two specific and nonspecific immune system tests. The cecal contents and liver were considered for C. Jejuni enumeration. According to the results, all treatments except one showed a significant difference from the control in terms of cecal colonization (P ≤ 0.001). Probiotic and Echinacea purpurea treatments could significantly increase the immune system's efficiency (P ≤ 0.001). In general, in this study we provide evidence that some commercial feed and water additives can reduce chickens' susceptibility to C. Jejuni colonization and also can effectively increase immune system efficiency.