The Oatley family, which has held the island for 20 years, hired investment bank UBS to "review options" for the holiday hotspot back in September.
"Over recent months the Oatley family undertook a strategic review of the opportunities and ownership of Hamilton Island in response to approaches from third parties," he told AFR.
"This review has now completed and the Oatley family has decided to keep Hamilton Island in its ownership, under the leadership of its exceptional management team."
AFR previously reported that the island could be worth around $1 billion in 2023.
Since Robert Oatley purchased the island for about $200 million in 2003, $450 million has been put into upgrading its tourism facilities.
Robert Oatley, who is better known as Bob, made his first fortune selling coffee and cocoa beans from Papa New Guinea internationally.
He then made $1.5 billion selling wine company Rosemount to Southcorp in 2001.
Hamilton Island is now run by the office of the family, Balmoral Australia, which is headed by Bob's son, Sandy Oatley.
Sandy's siblings, Ian and Rosalind, sit on the board, alongside ex-Virgin chief John Borghetti, former Deutsche Bank chief executive John Macfarlane and Guido Belgiorno-Nettis.
The island, which hosts five hotel accommodations with an annual occupancy of 75 per cent and a maximum capacity of 5000 guests, was first developed in the early 1980s.
It is the only one of the 74 Whitsundays Islands that is big enough to cater for a commercial airport.