  We present predictions for hadronic decays of the Higgs boson at
next-to-next-to-leading order (NNLO) in QCD matched with parton shower based on
the POWHEG framework. Those include decays into bottom quarks with full
bottom-quark mass dependence, light quarks, and gluons in the heavy top quark
effective theory. Our calculations describe exclusive decays of the Higgs boson
with leading logarithmic accuracy in the Sudakov region and next-to-leading
order (NLO) accuracy matched with parton shower in the three-jet region, with
normalizations fixed to the partial width at NNLO. We estimated remaining
perturbative uncertainties taking typical event shape variables as an example
and demonstrated the need of future improvements on both parton shower and
matrix element calculations. The calculations can be used immediately in
evaluations of the physics performances of detector designs for future Higgs
factories.
