The sculpture in Grosvenor Gardens, St Leonards, was damaged on Saturday night (June 25) and has been taken away to be repaired.
The duck is one of 51 sculptures that have been placed in areas of Hastings, St Leonards and Bexhill to raise funds for the hospice as part of the Follow that Duck event, which opened at the weekend.
A hospice spokesperson said: “Sadly one of our large ducks was vandalised on Saturday night and was removed for repair early on Sunday morning.
"It would appear that the sculpture has been forcibly wrenched from its plinth causing damage to the base of the sculpture. We are working with a local fibreglass specialist to undertake the necessary repairs.
"Other than this, the trail seems to have captured the hearts of Hastings and Rother with hundreds of people already on the hunt for our rubber ducks and ducklings.
"Our ducks have already been collected more than 5,500 times using the Follow that Duck app and maps are now available across the trail.”
People can walk the coastal trail to find the 30 large rubber ducks and 21 ducklings, which have been installed in their summer nesting sites, until September 4.
At the end of the trail, the giant ducks will be auctioned to raise funds for St Michael’s Hospice.
People can download the Follow that Duck app for £1.79 to help find them all and claim rewards from business supporters.
Each sculpture has been sponsored by a local business and hand decorated with an individually created design, a third of which have been painted by East Sussex artists.
The rubber ducklings have been designed and decorated by local schools and community groups.
Organisers on the Follow that Duck Facebook page said: “What an amazing opening weekend, the support from the public has been phenomenal. We have loved seeing how Follow that Duck is bringing so much joy to the community.
"We want to thank each and every one of you for all your support for Follow that Duck. Over 700 people have downloaded the app so far and it is currently trending 4th for paid apps in the Apple store.”