He is aiming to be in the dugout for Saturday's 2012 Africa Cup of Nations qualifier in Senegal although only to help Santos Mutubile, who will be in overall charge.
The Frenchman cut short his holiday in Greece in order to fly to Kinshasa to finalise the deal.
He replaces his compatriot Robert Nouzaret who quit on Wednesday.
"Claude LeRoy will be with the national side in Senegal along with assistant coaches Otis Ngoma and Santos Mutubile, who will be leading the squad there," Omari Selemani, President of DR Congo Football Federation, said.
Selemani also explained the departure of Nouzaret.
"We realised that his focus was more on players based in Europe rather than those who play at home," he said.
"This despite the fact we told him that we only like to use Europe-based players who are playing regularly for their clubs and who are in the under-20 and under-23 teams.
"We also agreed with Nouzaret that he should help train and develop his assistants but we noticed that he wasn't doing that, that's why we felt ready to terminate his contract by mutual consent."
LeRoy coached DR Congo to the 2006 Nations Cup but then decided against renewing his contact in April that year.