Khorasan mortar, a traditional, durable, and environmentally friendly building material, has been utilized for centuries in the Khorasan region of Türkiye. Its composition, which is based on natural hydraulic lime, imparts exceptional strength, breathability, and workability, making it suitable for diverse construction projects. Consequently, investigating the mechanical properties of Khorasan mortar, specifically its interaction with stone elements in historical buildings, in various mixing ratios, can provide valuable insights into the preservation and future of these architectural treasures. This study focuses on researching Khorasan mortar as a material of interest, utilizing brick ballast, lime, standard sand, water, and egg white, with a particular emphasis on egg white-stabilized Khorasan mortar. Four different water contents (70%, 80%, 90%, and 100%) were carefully selected, based on the dry mass of the egg white, to prepare a total of 12 samples (three identical samples for each water content) for testing. Prior to testing, the samples were cured for seven days in a desiccator. Unconfined compression strength tests were conducted, and axial strain-stress graphs were plotted to determine the unconfined compression strength (UCS) of the mixtures. The results revealed that the mixtures containing 80% water content exhibited the highest UCS values, while the samples with 90% and 100% water content demonstrated similar UCS values. The minimum UCS was approximately 0.518 times the maximum value, suggesting the importance of optimizing the water amount in Khorasan mortar formulations.