Ivory Coast's President Laurent Gbagbo has signed a decree creating a military structure that includes rebel forces.
Mr Gbagbo signed up to the peace deal two weeks ago
The new integrated command centre will include equal numbers of government troops and rebels, and will work to demobilise militias from both sides.
The initiative is one of the steps agreed in a recent peace deal aimed at ending years of civil war.
Ivory Coast has been split in half since the New Forces rebels seized the north of the country in 2002.
Two weeks ago Mr Gbagbo and rebel leader Guillaume Soro signed the peace deal in the capital of Burkina Faso, Ouagadougou, after months of negotiations.
It includes the creation of a transitional government by mid-April and elections afterwards.
Both sides say they have also reached agreement on an identification programme to give Ivorian identity papers to millions who do not have them.
But the BBC's James Copnall in Abidjan says there have been many failed agreements in the past.
The joint army command structure is the first and relatively painless sign that the two leaders intend to keep their word this time round.
But the Ivorian peace process has floundered so often that Ivorians are not overly optimistic, our correspondent adds.