Materials with AV3Sb5 (A = K, Rb, Cs) stoichiometry are recently discovered kagome superconductors with the electronic structure featuring a Dirac band, van Hove singularities, and flat bands. These systems undergo anomalous charge-density-wave transitions at TCDW∼80–100 K, resulting in the reconstruction of the Fermi surface from the pristine phase. Although comprehensive investigations of the electronic structure via quantum oscillations (QOs) have been performed on the sister compounds CsV3Sb5 and RbV3Sb5, a detailed QO study of KV3Sb5 is so far absent. Here, we report the Shubnikov–de Haas QO study in KV3Sb5. We resolve a large number of new frequencies with the highest frequency of 2202 T (occupying ∼54% of the Brillouin zone area in the kx–ky plane). The Lifshitz-Kosevich analysis further gives relatively small cyclotron effective masses, and the angular dependence study reveals the two-dimensional nature of the frequencies with a sufficient signal-to-noise ratio. Finally, we compare the QO spectra for all three AV3Sb5 compounds collected under the same conditions, enabling us to point out the similarities and the differences across these systems. Our results fill in the gap of the QO study in KV3Sb5 and provide valuable data to understand the band structure of all three members of AV3Sb5.