Christopher Tester, from Torquay, is said to be in a critical condition after he was wounded at his parents' restaurant on Christmas Day night.
Mr Tester, 37, is in an induced coma at Mount St John Hospital on the Caribbean island.
Friends have launched an appeal to raise Â£90,000 to fly him back to the UK for treatment.
Charlotte Williams, a friend of the family, told the Torquay Herald Express: "Time is of the essence. Please, please can you help us to raise funds for him.
"They need to raise Â£90,000. It will save his life. Please help us perform a Christmas miracle."
On its Facebook page, ABS Television in Antigua said that Mr Tester's expat parents Tony and Gill run the Boxer Shack restaurant in Old Road.
ABS posted a police statement that said the masked gunman shot Mr Tester in a struggle during a bid to rob the family.
A British man has been shot in the head during an attempted robbery in Antigua.