The first observation of the ωb-→Ξc+K-π- decay is reported using p p collision data at center of mass energies of 7, 8, and 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb-1. Four excited ωc0 baryons are observed in the Ξc+ K- mass projection of the ωb-→Ξc+K-π- decays with the significance of each exceeding five standard deviations. They coincide with the states previously observed in prompt pp and e+e- production. Relative production rates, masses, and natural widths of the states are measured, and a test of spin hypotheses is performed. Moreover, the branching ratio of ωb-→Ξc+K-π- is measured relative to the ωb-→ωc0π- decay mode and a precise measurement of the ωb- mass of 6044.3±1.2±1.1-0.22+0.19 MeV is obtained.