Thermoplastic elastomer (TPE) and thermoplastic vulcanizate (TPV) polyvinylchloride/acrylonitrile butadiene rubber (PVC/NBR) (70/30) blends containing 0, 0.5, 1, 1.5 and 2 phr graphene nanoplatelets (GnP) were prepared by melt mixing. The morphology and properties of resulting samples were investigated. Scanning electron microscopy (SEM) and transmission electron microcopy (TEM) techniques were employed for morphology studies. The progressive incorporation of GnP into PVC/NBR blends led to a gradual decrease in the size of NBR domains. TEM revealed fine distribution of GnP nanoplatelets in the blends. DMTA results showed a monotonic increase in storage modulus along with a steady decrease in damping factor with the GnP content in TPE and TPV nanocomposites. Mechanical properties revealed enhanced elastic modulus and ultimate strength at the cost of a fall in the elongation at break for TPE and TPV nanocomposites as a function of GnP loading. The swelling index of the samples declined with GnP content up to 1 phr after which the swelling index was not considerably affected by GnP up to 2 phr. A substantial increase in the electrical conductivity of the resulting nanocomposites was observed at GnP loadings higher than 1 phr. TPV samples demonstrated higher stiffness and strength along with lower extensibility, swelling indexes and electrical conductivity than their TPE counterparts.