Jet cross sections were measured in charged-current deep inelastic e±p scattering at high boson virtualities Q2 with the ZEUS detector at HERA II using an integrated luminosity of 0.36fb-1. Differential cross sections are presented for inclusive-jet production as functions of Q2, Bjorken x and the jet transverse energy and pseudorapidity. The dijet invariant mass cross section is also presented. Observation of three- and four-jet events in charged-current e±p processes is reported for the first time. The predictions of next-to-leading-order (NLO) QCD calculations are compared to the measurements. The measured inclusive-jet cross sections are well described in shape and normalization by the NLO predictions. The data have the potential to constrain the u and d valence-quark distributions in the proton if included as input to global fits. © 2008 The American Physical Society.