The aim of this article is to examine and document the Bursa Yıldırım Mosque handdrawn (kalemisi) decorations according to their design features after their lastest restoration work. Among the decoration types used in architecture, hand-drawn decorations, which are most susceptible to wear over time due to their characteristics, should be documented in the periods they were made and carried into the future. The decorations made with relief, carving, inlay and painting workmanship used on the plaster, wood, tile, ceramic, brick and stone walls in the building add value. In order to emphasize that the decorations in architectural structures are worth examining in detail, this article includes the present state of the hand-drawn decorations in the Bursa Yıldırım Beyazıt mosque, an important building belonging to the early Ottoman period, and examining the historical remains in terms of design principles. Within the scope of the research, only a limited number of studies on early Ottoman period architectural structures have been conducted and none have focused on hand-drawn types of decorations of Yıldırım Beyazıt mosque. So, it is important for this study that the works of the Yıldırım Beyazıt mosque include hand-drawn types of decoration as well as other kinds. Examining and determining the motif, color and technical aspects based on the hand-drawn samples in the selected architectural structure will be a document for the future and are among the aims of the research.