Portugal's Conceicao has led Cameroon into the play-offs of World Cup qualifying and took them to a third-placed finish at the Africa Cup of Nations on home soil last month.
Sports minister Narcisse Mouelle Kombi said Cameroonian President Paul Biya has ordered the national football federation to give the job to ex-Liverpool defender Song.
"On very high instructions from the President of the Republic, the coach of the men's national football team, Mr Antonio Conceicao, has been replaced by Rigobert Song," Kombi said in a statement.
"The Cameroonian Football Federation (Fecafoot) is invited to take the necessary measures for a rapid and harmonious implementation of these very high directives."