An adjustable shelving assembly includes at least two support rails, at least one geared rack provided in each of the at least two support rails, and an actuating mechanism placed adjacent to the at least one geared rack. The actuating mechanism is configured to support at least one shelf and facilitates movement of the at least one shelf along the at least two support rails. The actuating mechanism includes a pinion mating with the at least one geared rack, a plurality of permanent magnets mounted coaxially inside the pinion, ferromagnetic disks provided on either ends of the pinion, and a shaft placed axially in the pinion, connecting the permanent magnets. The permanent magnets magnetize or demagnetize the ferromagnetic disks when the shaft is rotated for locking or unlocking the at least one shelf.