  Dark Matter (DM) annihilation and decay during the Dark Ages can affect the
cosmic ionization history and leave imprints in the Cosmic Microwave Background
(CMB) anisotropy spectra. CMB polarization anisotropy can be sensitive to such
energy injection at higher redshifts and help reducing degeneracy with
primordial spectral parameters in $\Lambda$CDM and astrophysical ionization
processes during reionization. In light of a number of upcoming CMB
polarization experiments, such as AdvACTPol, AliCPT, CLASS, Simons Observatory,
Simons Array, SPT-3G, we estimate their prospective sensitivity in probing dark
matter annihilation and decay signals. We find that future missions have 95\%
C.L. projected limits on DM decay and annihilation rates to orders of
$\Gamma_\chi (\tau_{\chi}^{-1}) \sim 10^{-27}{\rm{s}}^{-1}$ and $\left<\sigma v
\right>/m_{\chi} \sim 10^{-29}{\rm{cm^3s^{-1}GeV^{-1}}}$ respectively,
significantly improving the sensitivity to DM from current experimental bounds.
