"This transaction is a significant first step in the plan ... To bring outside investors into the capital of its Brazilian subsidiary in order to strengthen its local ties and support its growth," Carrefour said in a statement.
Diniz was previously in partnership with Carrefour's French rival Casino, with which he shared control of his family business Pao de Acucar.
But that relationship soured when it emerged that the Brazilian magnate had approached Carrefour to merge their subsidiaries in Brazil, and Diniz eventually sold the remainder of his stake in Pao de Acucar to Casino.
The group has 256 outlets in Latin America's biggest economy and employs 72,000 people.