Clays have been used in various health care products, including drug delivery systems. Advanced formulations have been investigated to take full advantage of clays or clay-based materials. The remarkable properties of clays, such as high adsorption, high surface area and high ion exchange capacities, provide an ideal system for the delivery of poorly water-soluble drugs. Currently, there is still limited information on the classification and discussion of clay-based formulations for poorly water-soluble drugs. This review aims to describe efficient delivery systems that use clay as the main excipient in formulations. More details regarding the strategies of using clays in formulations as well as fabrication methods will be discussed. Moreover, combinations with other excipients in hybrid formulations will also be mentioned and the efficacy of these systems will be evaluated. The recent studies on claybased formulations for poorly water-soluble drugs provide fundamental approaches and prospects to be applied in drug development.