Yes—often the planter box itself can survive being accidentally left out in a freeze, but it is not guaranteed. The outcome depends on the material, how wet the soil was, whether drainage worked, how cold it got, and how long the freeze lasted. A sturdy plastic or resin planter with good drainage and some insulation is likely to come through. Wood can survive too, but wet wood may split as frozen soil expands. Glazed ceramic, terracotta, and thin concrete are more at risk of cracking or spalling. Thin metal may dent or bow, especially if the soil was saturated.
The plants are usually more vulnerable than the box. Roots and crowns can freeze in a container because the root ball is exposed to cold from all sides. Hardy perennials may still make it, especially if the pot is large and mulched; tender plants and evergreens often suffer. Do not move or bang a frozen planter—cold materials can be brittle.
After the thaw, check for cracks, bowing, loose bands, separated joints, and water pooling. If the box is cracked but still holding soil, use it temporarily and plan to repot. Improve drainage, empty saucers, elevate the planter, add mulch, group pots, and use a windbreak. If a plant looks dead, wait until spring before pruning, because some roots may recover. In short, an urban planter box can survive a freeze, but inspect it after thaw and expect plant losses to be the bigger issue.