Klebsiella pneumoniae is one of the major pathogens responsible for multiple infections in clinical settings，and especially, the emergence of highly pathogenic variant known as hypervirulent K. pneumoniae (hvKp) poses an increasing threat to public health worldwide. The increased virulence of hvKp is mediated by an array of virulence factors, among which the capsular polysaccharides (CPS) play the most vital role as the decisive immune evasion factor during infection process. In addition, the overproduction of CPS facilitates the formation of another representative virulence phenotype, hypermucoviscosity (HMV), which is commonly characterized by an intrinsic sedimentation resistance. Notably, both hypercapsule and HMV are strongly associated with the increased virulence of hvKp isolates. In recent years, the frequent emergence of K. pneumoniae strains exhibiting both hypervirulence and multidrug resistance has severely undermined current anti-infective strategies, underscoring the urgent need for alternative treatment approaches. Here,benzoic acid (BA) was identified as an effective capsule inhibitor capable of significantly attenuating both capsule production and mucoid phenotype in various hypervirulent strains. Treatment with BA markedly increased the sensitivity of bacteria to environmental stress and the killing by host-derived antibacterial molecules such as the antimicrobial peptide LL-37 and complement system. Meanwhile, capsule-mediated resistance to cellular adhesion and phagocytosis were also pronouncedly impaired by BA. BA treatment increased the survival rates by 40% in larvae infected; BA (50 mg/kg) effectively reduced mortality induced by wild-type K7 strain from 100% to 50%, whereas the ΔGT-1 K7 mutant did not cause mortality, with a survival rate of 100%. In conclusion, these findings provide a basis for the development of capsule-targeting therapeutics and warrant further investigation into the molecular mechanisms of BA action for combating hypervirulent K. pneumoniae infections.