Sustainability is essential for future technologies to harmonize with our living environment. Cellulose is one of nature's most abundant natural polymers, being the main chemical components of wood and plants. It recycles back to nature by composting over a short period of time. Recently, cellulose has been rediscovered as an active material, namely electroactive paper (EAPap). This chapter reviews the fabrication and actuation principles of EAPap and its three subareas in terms of piezoelectric EAPap, ionic EAPap and hybrid EAPap, along with their applications. Cellulose is known to have piezoelectric and ion migration effects and these two effects can be maximized, which results in piezoelectric EAPap and ionic EAPap. To further improve the functionality of cellulose, hybrid composites of inorganic functional materials are introduced by incorporating carbon nanotubes (CNTs), titanium dioxide (TiO₂) and tin oxide (SnO₂) with cellulose. Since cellulose is biocompatible, sustainable, biodegradable, capable of broad chemical modification, hydrophilic and has high mechanical strength and stiffness, various cellulose-based devices are possible.