A foldable multi-purpose container filler includes a sheet of material that may be reversibly convertible between a compact form for storage or packaging and an expanded form to fill a container opening (e.g., bag, drinkware, vase, etc.). The container filler includes fold lines or creases that dictate the compact form and the expanded form and allow for reversible conversion between the forms. In addition, the container filler includes connectors for securing the container filler to a container, as well as a base to support the container filler upright on a surface absent a container.