Cdre Bainimarama, who seized power in a military coup in 2006, told the nation in his New Year's Day address that the new constitution would be completed by the end of March.
"The new, modern and enduring constitution will be ready by the end of the first quarter of 2013," he said.
But he also announced as part of the constitutional review the country would get a new flag.
"All of this is to reflect a sense of national renewal, to reinforce a new Fijian identity and a new confidence in being Fijian on the global stage," Cdre Bainimarama said.
The current flag, adopted in 1970, features the Union Jack in the top left-hand corner and a shield from Fiji's coat of arms on a sky-blue background.
Cdre Bainimarama tore up the previous constitution in 2009 and has promised to hold elections in 2014.
In his address he said the new constitution would lay the framework for next year's vote.
"A constitution that must ensure common and equal citizenry and a constitution that just ensure that any representatives of the people in the new parliament must be elected under the principle of one person, one vote and one value," he said.