The unique functionalities of polyelectrolyte brushes depend on several types of specific interactions, including solvent structure effects, hydrophobic forces, electrostatic interactions, and specific ion interactions. Subtle variations in the solution environment can lead to conformational and surface structural changes of the polyelectrolyte brushes, which is discussed mainly from a surface interaction perspective in this review. A brief overview is given of recent theoretical and experimental progress on the structure of polyelectrolyte brushes in various environments. Two important techniques for surface force measurements are described, the Surface Forces Apparatus (SFA) and the Atomic Force Microscope (AFM), and some recent results on polyelectrolyte brushes are shown. Lastly, this review highlights the use of these surface‐grafted polymer films to create functional surfaces for various applications, including non‐fouling surfaces, boundary lubricants, as well as stimuli‐responsive surfaces.