It is the first stage of a nationwide disarmament programme that is expected to last three months.
A coup in 1999 and years of uprisings led to a war in 2002 between rebels of the Ivory Coast Patriotic Movement and the government.
The country was then divided with the rebels holding the north and the government in control of the south.
"There is no more battle-front in Ivory Coast," said Laurent Gbagbo, the president, standing next to Guillaume Soro, the prime minister and former leader of the Forces Nouvelles (FN), a rebel group.
The ceremony was held on Saturday in the central market town of Tiebissou, a former buffer zone separating the north and south.
Ivory Coast, the world's principal cocoa producer, was split in half by a 2002 rebellion against Gbagbo, with international peacekeepers monitoring the north-south buffer zone that is in the process of being dismantled.
Describing the disarmament process involving FN forces and pro-government fighters as the "last segment" of the March peace accords, Gbagbo said: "I really hope elections will take place at the end of June.
"We are galloping towards the elections."
Güncelleme Tarihi: 23 Aralık 2007, 10:50
A peace treaty signed in March in Burkina Faso - one of several signed by the two sides to reunite the country after the war - called for holding presidential elections in 2008 and gave a general timeline for disarming militias and FN forces.
Gbagbo's mandate officially expired in 2005, but he has remained in power, with proposed elections pushed back several times.
But like other parts of the Ouagadougou agreement, the disarmament process has been delayed.
The two sides previously hosted two disarmament ceremonies in the western town of Guiglo in May, and the northern rebel stronghold of Bouake in July.
But the next step in the process - full disarmament, demobilisation and reintegration of former fighters into the government forces - were not taken.
The two sides signed a new agreement in November on regrouping their forces, withdrawing and stocking weaponry and dismantling militia groups as of December 22.
The process will be overseen by a command centre based in Yamoussoukro, the political capital, under the supervision of UN peacekeepers and French troops under Operation Licorne (Unicorn).
The latest agreement also provides for the extension of a government administration across the whole country to be completed at the latest on January 30, 2008.
In addition, ex-fighters are to benefit from a job-training programme to be launched in January and an allowance for the first three months of the disarmament process.