  We study stochastic gravitational waves from cosmic strings generated in an
ultraviolet-complete model for pseudo-Nambu-Goldstone dark matter with a hidden
$\mathrm{U(1)}$ gauge symmetry. The dark matter candidate in this model can
naturally evade direct detection bounds and easily satisfy other
phenomenological constraints. The bound on the dark matter lifetime implies an
ultraviolet scale higher than $10^9~\mathrm{GeV}$. The spontaneous
$\mathrm{U(1)}$ symmetry breaking at such a high scale would induce cosmic
strings with high tension, resulting in a stochastic gravitational wave
background with a high energy density. We investigate the constraints from
current gravitational wave experiments as well as the future sensitivity. We
find that most viable parameter points can be well studied in future
gravitational wave experiments.
