We investigate the effects of the kaon cloud on the electromagnetic and axial-vector form factors of the $Omega^-$ baryon within the framework of the chiral quark-soliton model. We first derive the profile function of the chiral soliton in such a way that the kaon Yukawa tail is properly produced self-consistently. Then, we compute the electromagnetic form factors of the $Omega^-$ baryon. The results for the electromagnetic form factors are compared with the lattice data. We find that the results with kaon tail employed are in far better agreement with the lattice data. We also study the axial-vector form factors of the $Omega^-$ baryon, examining the effects of the kaon cloud.