Upconversion nanoparticles emit visible light when excited by near infrared radiation, making them suitable for many applications such as bioimaging, three-dimensional displays, solid-state lasers, etc. In this work, freestanding thin films, which can be fabricated by combining layer-by-layer (LbL) assembly and a sacrificial method, will be utilized to incorporate upconversion Yb ³⁺, Er³⁺ doped NaYF₄ nanoparticles into multilayer thin films. LbL is a versatile method to prepare nanoscale multilayer thin films by alternately depositing positive and negative charged functional building blocks onto solid substrates. These lanthanide doped NaYF₄ upconversion nanoparticles are capped with oleic acid and can be converted from hydrophobic to hydrophilic particles by extraction into a citric acid solution. The surface modified upconversion nanoparticles are uniformly deposited in the LbL thin films. A variety of techniques, e.g. atomic force microscopy (AFM), scanning electron microscopy (SEM), UV-VIS spectroscopy, etc. was used for characterization of the nanocomposite multilayer thin films.