A telescoping insulated box assembly including an outer box including a plurality of outer side walls, the plurality of outer side walls including a first outer side wall including a first outer side panel, a first inner side panel, a first connecting strip, and a tab, the first connecting strip joined to a top of the first outer side panel by a first fold line and a top of the first inner side panel by a second fold line, the first outer side panel, the first inner side panel, and the first connecting strip at least partially defining a first insulation cavity within the first outer side wall, the tab joined to a side of the first inner side panel by a third fold line; and a second outer side wall including a second outer side panel, a second inner side panel, and a second connecting strip.