The former PM, Eugene Mangalaza, was dismissed as Mr Rajoelina said he could no longer work with him.
Mr Rajoelina, a former DJ, came to power with military backing earlier this year.
He overthrew Marc Ravalomanana after weeks of demonstrations that left dozens dead.
New PM’s call
Mr Rajoelina had agreed in November on appointing Mr Mangalaza after talks with his rivals that were mediated by African leaders.
But the power-sharing deal has fallen apart, with Mr Rajoelina and three former presidents bickering over the division of key jobs in a government.
In an address broadcast across the nation, Col Camille called on the opposition to work with the government.
He said his priorities were to deliver security and organise elections.
Mr Rajoelina has pledged to hold a general election on 20 March.
Source: Allafrica