  In this paper, we present ${\tt SGK18}$ FFs, a first global QCD analysis of
parton-to-{\it unidentified} charged hadrons fragmentation functions (FFs) at
next-to-next-to-leading order (NNLO) accuracy in perturbative QCD. This
analysis is based on single-inclusive charged hadron production in
electron-positron ($e^-e^+$) annihilation. The uncertainties in the extraction
of ${\tt SGK18}$ FFs as well as the corresponding observables are estimated
using the "Hessian" technique. We study the quality of the {\tt SGK18} FFs
determined in this analysis by comparing with the recent results in literature.
We also show how {\tt SGK18} FFs results describe the available data for
single-inclusive unidentified charged hadron production in $e^-e^+$
annihilation. We demonstrate that the theoretical uncertainties due to the
variation of the renormalization and factorization scales improve when NNLO QCD
corrections are considered. We find that the resulting {\tt SGK18} FFs are in
good agreement with all data analyzed and the inclusion of NNLO corrections
tends to improve the data description with somewhat smaller uncertainty.
