A type of button accordion where the melody-side keyboard consists of rows of buttons arranged chromatically, while the bass-side keyboard is usually the Stradella system. There can be 3 to 5 rows of vertical treble buttons. In a 5-row chromatic, 2 additional rows repeat the first 2 rows to facilitate options in fingering. It is unisonoric, meaning the same note is sounded whether the bellows are pushed or pulled. Included among chromatic button accordions is the Russian bayan.

Comparing the layout to the piano accordion, the advantages of a chromatic button accordion are the greater range and better fingering options. On the other hand, some fingering positions require twisting of the wrist and the aspect of alternative fingering patterns may make sight reading difficult.

The chromatic button accordion is traditionally used in a concert setting and is more popular in jazz and classical music because it can be freely played in any key, usually with identical fingering patterns.