This book constitutes the refereed proceedings of the 15th International Conference on Artificial Intelligence in Music, Sound, Art and Design, EvoMUSART 2026, held as part of EvoStar 2026, in Toulouse, France, during April 8-10, 2026. The 13 full papers together with 15 short papers presented in this book were carefully reviewed and selected from 58 submissions. The EvoMUSART 2026 cover a wide range of topics and application areas, including generative approaches to music, visual art and design. There is a growing interest in the application of these techniques in fields such as visual art and music generation, analysis and interpretation; sound synthesis; architecture; video; poetry; design; and other creative tasks.