Song, who played as a central defender for his country at four World Cups and then coached the Indomitable Lions at the finals in Qatar in 2022, takes over from the Swiss coach Raoul Savoy, who was fired in October during their unsuccessful Africa Cup of Nations qualifying campaign.
They are, however, still involved in World Cup qualification and resume their campaign in March with home matches against Madagascar and Mali.
The Central African Republic sit in fifth place in Group I with four points from four matches, five behind co-leaders Comoros and Ghana.
Song, whose club career took in spells at Liverpool, West Ham United, Racing Lens and Galatasaray, had a confrontation with Andre Onana during the last World Cup that led to the goalkeeper leaving the tournament in Qatar.