  We study a scalar singlet dark matter (DM) having mass in sub-TeV regime by
extending the minimal scalar singlet DM setup by additional vector like
fermions. While the minimal scalar singlet DM satisfies the relic and direct
detection constraints for mass beyond TeV only, presence of its portal coupling
with vector like fermions opens up additional co-annihilation channels. These
vector like fermions also help in achieving electroweak vacuum stability all
the way up to Planck scale. We find that for one generation of vector like
quarks consisting of a $SU(2)_L$ doublet and a singlet, scalar singlet DM with
mass a few hundred GeV can indeed satisfy relic, direct detection and other
relevant constraints while also making the electroweak vacuum absolutely
stable. The same can be achieved by introducing vector like leptons too, but
with three generations. While the model with vector like quarks is minimal, the
three generations of vector like lepton doublet and neutral singlet can also
give rise to light neutrino mass at one loop level.
