Alice Nine's musical style can mainly be described as rock, with touches of metal, and a few instances of dance music. Their works range diversely, including heavier songs that were more prevalent in their early career, emotional ballads and medium tempo songs, and the lighter rock sound marked with more melodic instrumentation and synthesizers that is present on their 2007 album, Alpha. Like some other Visual Kei bands, as they progressed through the years, the band experimented and released songs that focus more on the mainstream public.

The band's appearance and shift from a heavy visual kei look also took place over the length of their career. In early work, Alice Nine's clothing in promotional footage and live concerts was a sort of stylized take on traditional Japanese clothing, along with moderate makeup, piercings, and bright hair colors such as red and pale blonde. However, in 2006, the look began to fade out and essentially disappeared the year after, having been replaced with leather and the onset of street fashion. Music videos for "Blue Planet" and "Gekkou Yoku" show off a relaxed and casual look, while videos such as those for "Cosmic World" and "Rainbows" are examples of forays into street fashion.