Recent advances in genetic transformation techniques enable the production of desirable and novel flower colors in some important floricultural plants. Genetic engineering of novel flower colors is now a practical technology as typified by commercialization of a transgenic blue rose and blue carnation. Many researchers exploit knowledge of flavonoid biosynthesis effectively to obtain unique flower colors. So far, the main pigments targeted for flower color modification are anthocyanins that contribute to a variety of colors such as red, pink and blue, but recent studies have also utilized colorless or faint-colored compounds. For example, chalcones and aurones have been successfully engineered to produce yellow flowers, and flavones and flavonols used to change flower color hues. In this review, we summarize examples of successful flower color modification in floricultural plants focusing on recent advances in techniques.