Involved in ciliogenesis. It is required for appropriate acetylation and polyglutamylation of ciliary microtubules, and regulation of cilium length (By similarity). Acts as a positive regulator of hedgehog (Hh)signaling (By similarity). Localized to the proximal region in cilia. Stimulation of Hh signaling leads to redistribution of ARMC9 toward the ciliary tip within 6 hours, follow by a gradual return to its original proximal location (By similarity). Localizes to the daughter centriole of the primary cilium in RPE1 cells (By similarity).