Ravalomanana made the announcement in South Africa on Thursday, where he has lived in exile since 2009 when President Andy Rajoelina seized power in the world's fourth largest island with military backing.
Ravalomanana's overthrow triggered a political crisis that has hammered the cobalt and nickel producing island's economy and seen government spending fall dramatically after donors froze aid worth hundreds of millions of dollars.
"I will return home the day after tomorrow, which is Saturday. Here are the tickets," he said at a news conference, holding up a batch of air tickets.
The move comes two weeks after regional mediators indicated a breakthrough was imminent in the political deadlock in the country, the world's largest vanilla producer.
"I return to my country humbly, so we can return to democracy, and together, create a bright future for Madagascar," Ravalomanana said. Rajoelina denounced Ravalomanana's planned return as an act of provocation aimed at destabilizing the country.
"We will have to take action. At a given time, we will look for him so that he serves his prison sentences," the former disc-jockey told a news conference in Antananarivo.
Last year, Ravalomanana was sentenced in absentia to life imprisonment for the deaths of 30 protesters killed by the presidential guard as they marched on the presidential palace.
Thomas Wilson, senior Africa analyst at Control Risks, said he doubted if Ravalomanana had been able to cut a deal with Rajoelina, who has been reluctant to engage with him.
"His return is the last roll of the dice of a desperate man and it's very likely that the plane will not take off," Wilson said.
Analysts say his return would risk polarizing the island.
Ravalomanana said he was unsure if Madagascar should go ahead with elections in the next few months. "I am not sure about elections in May. If it is going to be May, voter lists will not be ready," the self-made millionaire said.
In earlier mediation efforts, Ravalomanana pledged not to contest the next election.
So too did Rajoelina, 36, although the country's new constitution, approved in a November referendum, lowers the minimum age for a president by five years to 35, allowing Africa's youngest head of state to stand if he chooses.
The new basic law also requires presidential candidates to be resident in the country for six months ahead of a poll.
"I know the risks facing my return but I cannot allow them to get in the way of us restoring democracy. I have nothing to fear. I have done nothing wrong," he said.
