Campylobacter spp. are considered the leading bacterial cause of human gastroenteritis in the world. The development of effective intervention strategies aimed at limiting C. jejuni infections has encountered various challenges, including a lack of an appropriate animal model. Nevertheless, recent advancements in research have clarified the molecular mechanisms underlying C. jejuni’s pathogenicity, potentially opening new avenues for targeted interventions. This study evaluated the efficacy of a ferric sillen core-linked polymer (FSCLP) in lowering the proliferation and gene expression of C. jejuni virulence factors in vitro. Furthermore, this study sought to examine the impact of this FSCLP in an ex vivo environment by investigating its ability to influence the attachment to and invasion of porcine jejunal epithelial (IPEC-J2) cells by C. jejuni. Findings show that the FSCLP exhibits significant inhibitory effects on the growth of C. jejuni (p < 0.001) and decreases gene expression related to both virulence and colonisation in C. jejuni. Moreover, supplementation with the FSCLP significantly reduced the attachment of C. jejuni to IPEC-J2 cells (p < 0.01) when compared to the control. Thus, this water-soluble product presents a potential management strategy for Campylobacter infections in poultry, potentially impeding colonisation, reducing transmission, and ultimately mitigating the incidence of human campylobacteriosis.