Understanding the cellular uptake of nanomaterials (NMs) is a fundamental and critical issue for uncovering biomedical effects of NMs and facilitating their practical applications in the clinic. In this Review, by highlighting the differences of NMs cellular uptake between in vitro and in vivo, a focus on reviewing recent works about the effects of four physicochemical parameters of NMs (size, rigidity, shape, surface modification) on regulating NMs cellular uptake in vitro and in vivo is undertaken. This review can provide readers some useful clues and new thinking for understanding NMs cellular uptake in depth.