Active disturbance rejection control (ADRC) has been developed as an enabling technique to reduce the influence of both unmodeled uncertainties and disturbances. The key idea of ADRC is a data-driven mechanism through the extended state observer (ESO), to timely estimate the affect caused by unknown unmodeled uncertainties and disturbances. As ADRC in its nature is a model-guided data-driven method, the potential of ADRC has been gradually discovered in industry, leading to many successful applications such as manufacturing, process control, robotic systems, and energy systems. Driven by some top companies such as Texas Instruments, FreeScale, Danfoss, and so forth, ADRC has been recognized as one effective alternative control method to the dominant one: proportional-integral-derivative (PID). Hence the research on ESO/ADRC based control and its application have world-wide interest.The aim of the special issue on "Active Disturbance Rejection Control: Practical Technology and Industrial Application" is to bring together papers of ADRC with different design principles and multifarious industrial applications. Moreover, the special issue is to present the latest developments in design methods, performance analysis, and implementation technologies for ADRC and other disturbance rejection methods. Also, the issue provides an international platform for scholars in ADRC field to exchange and discuss novel ideas by submitting and reviewing contributions.Eight papers were eventually selected from a number of submissions through a strict peer-reviewed procedure. These papers are featured with ADRC based novel designs or appealing technologies to achieve disturbance/uncertainty estimation as well as attenuation. Despite different focuses, almost all papers contain both theoretic developments and successful applications. To make them easy for the reference, the selected contributions will be briefly introduced as follows.The articles 1-3 aimed to propose new ADRC methods for different kinds of uncertain plants. Li and Wang 1 constructed a fuzzy active disturbance rejection controller (FADRC) for autonomous underwater vehicle manipulator system (AUVMS). The FADRC was designed to estimate and compensate the total disturbance with fuzzy rules of parameters tuning. Moreover, in typical control tasks, the simulation results showed that FADRC can achieve better performance and consume less energy than classic fuzzy logic controllers and traditional linear ADRC. Zhao et al. 2 focused on designing nonlinear ESO for output tracking of a class of uncertain nonlinear affine systems. By using some special nonlinear functions of estimation error in ESO, more accurate estimation and smaller peaking value were achieved. The system output was capable to track the given reference signal despite a large scope of nonlinear uncertainties, which was shown by both theory and simulation. In Reference 3, an improved ADRC was conceived for output tracking of uncertain plants with unknown control direction. Without assuming the knowledge of the cont...