Maloney, who guided Lennox Lewis to the world heavyweight title, said yesterday she was now living as a woman called Kellie.
Boxing fans, including the author Irvine Welsh, gave their support. Welsh said: "All the best to Kellie, formerly Frank Maloney, in her new life.
"Great achievements happen in boxing, as elsewhere, irrespective of gender."
Former footballer Stan Collymore also tweeted his support, adding: "Being who he wants to be after 61 years.
"Nobody deserves to begrudge him happiness."
Irish boxer Jeff Thomas wrote: "Came on expecting loads of Frank Maloney abuse and the vast majority is positive - fair play to him that took a lot of courage. Be happy."
Boxing promoter David Coldwell added: "When I think back to how miserable Frank Maloney was when we crossed paths, maybe this was the reason and not boxing ... Hope he's happy now."
Maloney said that she had long felt she was born into the wrong body. "I can't keep living in the shadows," she added.