Thorpe has reportedly told several close friends that he would be returning to the pool and would be lodging drug-testing paperwork with Swimming Australia tomorrow.
Thorpe needs to declare his return to racing by the end of May as FINA regulations stipulate he must be available for anti-doping testing for nine months to be eligible to compete at the Olympic selection trials in March 2012.
Thorpe, 28, will compete in those trials in his attempt to make the London team.
He retired in 2006 after claiming he had his motivation to compete at the highest level.
Manager David Flaskas said Thorpe would address the media in Sydney "about his swimming future."
"He'll let everyone know tomorrow," Flaskas said.
"Come along to the press conference and Ian can say what he wants to say."
Speculation has mounted since Thorpe has been spotted in recent months regularly training at a Sydney pool.
Flaskas said last month that Thorpe was inspired by Geoff Huegill's comeback at the Delhi Commonwealth Games.
"Ian is a competitive guy, and if he was to make a return, he would be doing it for his own reasons," he said.
Australian head coach Leigh Nugent has confirmed that Thorpe has been in regular contact.
January 2011: Ian Thorpe encouraged to make comeback for London 2012