<p>Drying is one of the most crucial post-harvest stages in herbal plant processing because it determines the stability of bioactive compounds and the quality of the final product. Conventional drying methods often degrade thermolabile active compounds due to excessively high temperatures or excessively long drying times. A solid desiccant-based dehumidification drying system offers an alternative approach that allows moisture removal at moderate temperatures and low relative humidity, thus maintaining product quality. This review article discusses the basic principles of dehumidification drying systems, types of solid desiccants, and the quality of dried herbal plants. Furthermore, the drying characteristics and modelling of herbal plant drying kinetics using dehumidification systems are reviewed to provide a comprehensive understanding of the drying behavior. Among the available desiccants, silica gel is a widely used choice for drying herbal plants. Empirical and semi-theoretical models, particularly the Page model, have been shown to best describe the drying kinetics of herbal plants in dehumidification drying systems, both for herbal leaves and rhizomes. The dehumidification drying system not only accelerates drying but also maintains phenolic, flavonoid, and essential oil contents than hot-air or solar drying methods. Optimization parameters, such as air flow rate, desiccant mass, and temperature, are required for industrial-scale applications. Integration with renewable energy and the utilization of summer waste is also recommended to support environmental sustainability.</p>