Over the past few decades, a new branch of plasma research, nanomaterial (NM) synthesis through plasma–liquid interactions (PLIs), has been developing rapidly, mainly due to the various, recently developed plasma sources operating at low and atmospheric pressures. PLIs provide novel plasma–liquid interfaces where many physical and chemical processes take place. By exploiting these physical and chemical processes, various NMs ranging from noble metal nanoparticles to graphene nanosheets can easily be synthesized. The currently rapid development and increasingly wide utilization of the PLI method has naturally lead to an urgent need for the presentation of a general review. This paper reviews the current status of research on PLIs for NM synthesis. The focus is on a comprehensive understanding of the synthesis process and perceptive opinions on current issues and future challenges in this field.