The background of this article is to develop formulations consisting of natural raw materials that are effective in diaper rash by taking advantage of the medicinal properties of zinc oxide, natural oils, and beeswax. The purpose of this research was to determine the appropriate amounts of the constituents of the formulation and to determine the optimum formulation by comparing the margin of safety (MoS), and microbiological and physicochemical properties of the best formulation. For this purpose, parameters such as pH, rheological behavior, hydrophilic and lipophilic balance (HLB), zeta potential, and polydispersity index were analyzed and evaluated to determine the optimum formulation. Besides, microbiological reproduction and 3-month stability studies of the developed product were carried out, and it has been proven that the developed product maintains both microbiological and stability properties throughout its shelf life. Furthermore, whether each raw material used in the selected optimum formulation remained within MoS values was evaluated according to exposure doses in the literature. Whether it maintains the desired properties throughout the shelf life was evaluated by stability studies. In this article, eight different zinc oxide-based formulations for preventing diaper rash were developed, and their physicochemical properties were examined to optimize cream formulations. baby barrier cream (BBC)-8 was chosen as the ideal formula by comparing all the parameters obtained as a result of the analysis. As a result of the optimization studies of the BBC-8 formulation, the pH value was 7.2, the viscosity property was pseudoplastic-type flow, the particle size was 533.2 nm +/- 6.93, and the zeta potential was -30.9 mV +/- 0.72. The theoretical safety assessment of each constituent has been made according to the European Union Cosmetics Directives. According to the calculations made on each raw material in BBC-8 according to the directives, the MoS value was found to be more than 230. For the stability studies, no microbiological growth was observed at the end of the 3-month stability studies at 25 and 40 degrees C. In terms of the development of future natural cosmetic product formulations and the definition of "natural formulation," it gives hope to prepare a safer cosmetic product for baby rash creams that do not contain preservatives, perfumes, and dyes and consists of natural oils and zinc oxide.