Extensions of the Two Higgs Doublet model with a complex scalar singlet (2HDMS) may accommodate all current experimental constraints and are highly motivated candidates for Beyond Standard Model Physics. In this work, we focus on the phenomenology of the 2HDMS with the complex scalar singlet as the dark matter candidate. We study variations of dark matter observables with respect to the model parameters and present representative benchmark points allowed by existing experimental constraints from dark matter, flavour physics and collider searches. Further, we discuss the discovery potential of observing such scenarios at future colliders.