[en] We calculate next to leading order QCD corrections to semi-inclusive polarized deep inelastic scattering and e⁺e^- annihilation cross sections for processes where the polarization of the identified final-state hadron can also be determined. Using dimensional regularization and the HVBM prescription for the γ₅ matrix, we compute corrections for different spin-dependent observables, both in the MS and MS_p factorization schemes, and analyse their structure. In addition to the well-known corrections to polarized parton distributions, we also present those for final-state polarized fracture functions and polarized fragmentation functions, in a consistent factorization scheme. (orig.)