An insulated drinking vessel, e.g., a tumbler, and method of making the same is disclosed. The vessel basically comprises a pre-molded inner vessel formed of a plastic material having a sidewall is disposed within a pre-molded outer vessel formed of a plastic material having a sidewall to form a subassembly having an insulating air space between the sidewalls. A ring of plastic material is molded in-situ on top portions of the inner and outer vessels of the subassembly to cause portions of the plastic material of the inner and outer vessels to melt and intermingle with the plastic material of the ring to form a non-superficial homogenous joint. The ring forms the rim or lip of the insulated drinking vessel.