This critical review provides an overview of the main advantages related to conventional and unconventional hydro(solvo)thermal approaches for novel advanced materials design. This versatile synthetic strategy has been industrially used since the nineteenth century, making it possible to obtain several crystals with a high level of purity that in turn cannot be achieved by other synthetic methods . We can highlight that, although there are a lot of unknowns on the anisotropic crystal growth, the conventional and unconventional hydro(solvo)thermal approaches are relatively simples and low-costs and have displayed a prominent role in the development and discovery of new advanced materials with entirely new physical/chemical properties and unique multi-functionalities for many technological applications. In this direction, the continuous advances in this research field, in particular, have more recently led to the integration of machine-learning algorithms to predict hydro(solvo)thermal reaction outcomes leading to a success rate of about 89 percent . Thus, we anticipate that these advances will contribute so that in the future we can select the better materials for a particular technology application of interest, as well as we will have the ability to predict the experimental conditions to obtain their desired structure-composition-morphology. Furthermore, we can also conclude that diverse highly complex structures can be directly synthesized from such strategies, which provide a feasible approach for creating a huge variety of advanced materials, as summarized in this review.