A quick release down-the-hole (DTH) hammer drill bit assembly includes a drill bit releaseably retained at a drive transmission component (drive sub) via a retaining sleeve and respective retaining formations to axially couple and lock the drill bit at the assembly. In particular, the drill bit is retained exclusively at the assembly via retaining formations at the drive sub, the sleeve and the drill bit, without a requirement for additional retaining rings that would otherwise axially lock the drill bit at the drive sub.