Sponges are dominant components of coral reef ecosystems, often exceeding reef-building corals in abundance. Large sponges, often more than 1 m in diameter, may be hundreds to thousands of years old. When damaged or dislodged, large sponges usually die because they are unable to reattach to the reef substratum. Because suitable methods for reattaching dislodged sponges are lacking, they are typically excluded from coral reef restoration efforts. Here we present a novel technique for the reattachment of large sponges that was tested using the Caribbean Giant barrel sponge, Xestospongia muta. Transplants of X. muta were conducted at 15- and 30-m depth off Key Largo, Florida. Despite the active hurricane season of 2005, 90% of deep and 35% of shallow transplants survived, with nearly 80% reattaching to the substratum and growing after 2.3–3 years. This technique may be generally adapted for securing large sponges in coral reef restoration efforts.