Abstract In Anatolia, significant developments have been observed in mosque architecture and ornamentation from the acceptance of Islam to the present day. By the 21st century, different tendencies in mosque ornamentation have started to emerge. These approaches include: 1. original mosque ornamentation adopting the traditional style (authentic-traditional approach), 2. mosques ornamented by imitating admired mosques (copy approach), and 3. mosques with ornamentation emerging within the standards of modern architecture (contemporary approach). The purpose of this study is to examine the Turkish-Islamic decorative arts in mosques selected from Istanbul, Bursa, and Konya, built in the 21st century. These mosques have been analyzed in terms of the use of innovations in ornamentation designs and the understanding of contemporary style. In this context, content analysis, literature review, and on-site observation methods were used. Through this study, research was conducted on the proportionality and aesthetic satisfaction sought in mosque ornamentation, and suggestions were made. In this regard, three mosque cases were examined in terms of architectural elements such as the mihrab, minbar ornamentation, and decorative elements like calligraphy and hand-painted decorations. Accordingly, an analysis was conducted on the selection of materials for the mihrab and minbar, the reflection of these in the ornamentation, and the motifs and patterns used. In the hand-painted decorations examined, the composition and balance in their designs, color harmony, and the style influenced were considered. Another focus within our study was to examine the inscriptions in various locations of the mosques in terms of calligraphy art. As a result, it was found that the Şakirin Mosque has adopted an innovative-contemporary approach in the structure of its mihrab and minbar. The calligraphic panels and inscriptions were designed in a traditional style. It was determined that the Hafız Tayyar Arseven Mosque follows the traditional style with its mihrab, minbar, hand-painted decorations, and calligraphy, featuring an original design. The Bosnia Ulu Mosque, on the other hand, was built in a modern style and ornamented in a traditional style. Keywords: Modern Mosque, Turkish-Islamic Arts, Ornamentation, Turkey.