Abstract: A stackable toolbox assembly includes a parent toolbox and a child toolbox. The parent toolbox includes a top surface formed with a plurality of positioning grooves and defined by a plurality of regions. The child toolbox includes a bottom surface, which has an area identical to that one of the regions of the top surface of the parent toolbox, and a plurality of feet, each of which protrudes from the bottom surface of the child toolbox. When the child toolbox is disposed on the parent toolbox, each of the feet of the child toolbox extends into a corresponding one of the positioning grooves in the top surface of the parent toolbox, thereby interconnecting the parent and child toolboxes.