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<i>Klebsiella pneumoniae</i> (<i>K. pneumoniae</i>) exhibits the ability to form biofilms as a means of adapting to its adverse surroundings. <i>K. pneumoniae</i> in this biofilm state demonstrates remarkable resistance, evades immune system attacks, and poses challenges for complete eradication, thereby complicating clinical anti-infection efforts. Moreover, the precise mechanisms governing biofilm formation and disruption remain elusive. Recent studies have discovered that fingolimod (FLD) exhibits biofilm properties against Gram-positive bacteria. Therefore, the antibiofilm properties of FLD were evaluated against multidrug-resistant (MDR) <i>K. pneumoniae</i> in this study. The antibiofilm activity of FLD against <i>K. pneumoniae</i> was assessed utilizing the Alamar Blue assay along with confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and crystal violet (CV) staining. The results showed that FLD effectively reduced biofilm formation, exopolysaccharide (EPS), motility, and bacterial abundance within <i>K. pneumoniae</i> biofilms without impeding its growth and metabolic activity. Furthermore, the inhibitory impact of FLD on the production of autoinducer-2 (AI-2) signaling molecules was identified, thereby demonstrating its notable anti-quorum sensing (QS) properties. The results of qRT-PCR analysis demonstrated that FLD significantly decreased the expression of genes associated with the efflux pump gene (<i>AcrB</i>, <i>kexD</i>, <i>ketM</i>, <i>kdeA</i>, and <i>kpnE</i>), outer membrane (OM) porin proteins (<i>OmpK35</i>, <i>OmpK36</i>), the quorum-sensing (QS) system (<i>luxS</i>), lipopolysaccharide (LPS) production (<i>wzm</i>), and EPS production (<i>pgaA</i>). Simultaneously, FLD exhibited evident antibacterial synergism, leading to an increased survival rate of <i>G. mellonella</i> infected with MDR <i>K. pneumoniae</i>. These findings suggested that FLD has substantial antibiofilm properties and synergistic antibacterial potential for colistin in treating <i>K. pneumoniae</i> infections.