The current knowledge about the formation of layer‐by‐layer (LbL) self‐assemblies using combinations of nanocelluloses (NCs) and polyelectrolytes is reviewed. Herein, the fundamentals behind the LbL formation, with a major focus on NCs, are considered. Following this, a special description of the limiting factors for the formation of LbLs of only NCs, both anionic and cationic, and the combination of NCs and polyelectrolytes/nanoparticles is provided. The ability of the NCs and polyelectrolytes to form dense films with excellent mechanical properties and with tailored optical properties is then reviewed. How low‐density, wet stable networks of cellulose nanofibrils can be used as substrates for the preparation of antibacterial, electrically interactive, and fire‐retardant materials by forming well‐defined LbLs inside these networks is then considered. A short outlook of the possible uses of LbLs containing NCs is given to conclude.