Crohn's disease‒associated adherent-invasive Escherichia coli (AIEC) colonizes the gut lumen through Type 1 fimbriae. We demonstrated that the two-component signal transduction system BasRS is involved in the expression of fimbriae in the AIEC strain LF82, as evidenced by the reduced transcriptional activity of fimA in an LF82 mutant lacking BasRS. Consequently, the basRS mutant showed decreased invasiveness to HeLa cells, which was restored by introducing a plasmid expressing fimbriae in a BasRS-independent manner. These findings may provide new prospects for developing therapeutic interventions for AIEC-related Crohn's disease.