Abstract: Insulated shipping container with rabbet-joint side panels and the procedure for making the same. The insulated shipping container consists of an outer box and six insulated panels. The outer box is made of corrugated fiberboard. The insulated panels are made of expanded polystyrene foam with a thickness of at least 2 inches. The panels are cut with a hotwire machine and the rabbet-joint design locks the side panels in place, which gives the insulated container superb structural and thermal integrity. The box is assembled with a specific H-shape taping and the six panels are inserted to form the insulated container. The invention is the first to meet the packaging requirements of postal carriers and their insurance underwriters. The cost-effective manufacturing process allows for multiple container sizes without additional setup expense, which lowers the cost of shipping affected by dimensional weight versus actual rate shipping rates by the carriers.