Objective To characterize the molecular epidemiology of Campylobacter jejuni （C. jejuni） infections in foodborne diarreal cases in Baoshan District， Shanghai， and to explore the genetic evolutionary relationships among C. jejuni isolates.Methods Statistical and genomic analyses were performed on 68 C. jejuni isolates obtained from diarrheal cases at intestinal outpatient clinics in Baoshan District between 2023 and 2024. Based on whole-genome sequencing data， multilocus sequence typing （MLST）， clonal complex （CC） analysis， heatstable serotyping （HS）， and core-genome single-nucleotide polymorphism （SNP） phylogenetic analysis were conducted.Results The detection rate of C. jejuni was higher in spring and summer， with meat and meat products identified as the suspected food vehicles. A total of 46 sequence types （STs） were identified， which clustered into 16 clonal complexes （CCs）. The most prevalent CC was CC464， followed by CC574， and CC45. The predominant HS types were HS2， HS8/17， and HS5/31. Core-genome analysis revealed four pairs of isolates ≤5 SNP differences， and epidemiological investigation demonstrated a high degree of relatedness among these strains.Conclusion C. jejuni infections in the local population exhibit a higher detection rate in spring and summer， with meat and meat products as the primary suspected sources. Molecular epidemiology of these isolates shows a polyclonal distribution with evidence of short-chain transmission events. Integrating genomic sequencing into routine surveillance for rapid typing and cluster identification facilitates timely traceability and supports precise prevention and control of foodborne diseases.