This invention pertains to an improved adjustable kettlebell that has a stack of standard weight plates, a rounded grip section, a support bar serving to hold the weight stack, and flexible attachment members with cutouts for the support bar. The flexible attachment members provide a mechanically compliant clamping arrangement to accommodate weight stack of varying widths, and the cutouts allowing adjustment to the relative distance between the grip axis and the support bar axis. The improved adjustable kettlebell of the current invention serves as a close physical approximation to a solid cast kettlebell with a wide combination of standard weight plates.