  We construct a model containing a viable dark matter candidate, in the
framework of left-right symmetry, which can explain both width and
cross-section of the observed 750 GeV diphoton excess at the LHC. We introduce
a fermion quintuplet whose neutral component can be a possible dark matter
candidate, whereas the charged components enhance the loop induced coupling of
a 750 GeV singlet scalar with a pair of photons. We study the photo-production
of the singlet scalar and its various decay modes, successfully addressing both
the ATLAS and the CMS diphoton excess.
