Campylobacteriosis, most commonly caused by Campylobacter jejuni, is the most frequently reported bacterial gastroenteritis in the EU. The lack of adequate control measures for this pathogen exposes a major gap in the understanding of this bacterium. A particularly neglected area are bacterial interactions of C. jejuni. In this work we investigated the interactions of C. jejuni at different levels: (i) cell signaling within a population, (ii) interactions between C. jejuni strains, and (iii) inter-species interactions between Bacillus subtilis and C. jejuni. Within one population, we found that the inhibition of cell signaling affects motility, adhesion to polystyrene, and the invasion of C. jejuni into INT407 cells. By testing of 20 plant preparations we found that the strongest inhibitory effect was achieved by for the roseroot (Sedum roseum) extract. The study of C. jejuni inter-strain interactions reveled kin discrimination between C. jejuni strains. Less related strains (genetic similarity of 98.00 – 99.13 %) form a boundary line during swarming on soft agar. Kin discrimination affected the coaggregation of strains. The interaction of different strains was negative during co-cultivation and co-adhesion on polystyrene. The study of inter-species interactions revealed that the interaction between B. subtilis and C. jejuni negatively affects the growth and survival of C. jejuni in conditions that allow its growth. The strongest inhibitory effect was determined for B. subtilis PS-216. Our findings show that bacterial interactions have a strong effect on C. jejuni social interactions on all three studied levels. Modification of these interactions can contribute to the control of this pathogen in different environments.