  Spontaneous breaking of conformal symmetry has been widely exploited in
successful model building of both inflationary cosmology and particle physics
phenomenology. Conformal Grand Unified Theory (CGUT) inflation provides the
same scalar tilt and tensor-to-scalar ratio as of Starobinsky and Higgs
inflation. Moreover, it predicts a proton life time compatible with the current
experimental bound. In this paper, we extend CGUT to account for the production
of dark matter and the reheating of the Standard Model. To this end, we
introduce a hidden sector directly coupled to the inflaton, whereas the
reheating of the visible sector is realized through a portal coupling between
the dark particles and the Higgs boson. The masses and interactions of the dark
particles and the Higgs boson are determined by the form of the conformal
potential and the non-vanishing VEV of the inflaton. We provide benchmark
points in the parameter space of the model that give the observed dark matter
relic density and reheating temperatures compatible with the Big Bang
nucleosynthesis.
