It is okay to freeze yogurt, although there is no guarantee of the yogurt looking and tasting the same after freezing. Certain brands of yogurt respond to freezing in different ways.
To freeze yogurt successfully, keep it in an airtight container with some extra room because yogurt expands as it freezes. Freezing small cups of yogurt is acceptable as long as they are unopened. For the best results, transfer the yogurt to an airtight container if the cups are already open.
Thaw frozen yogurt by placing it in the refrigerator overnight or heating it in the microwave for a few seconds. Another suggestion is to freeze yogurt in ice cube trays to make a smoothie later.