Plassat, 62, head of private equity-backed retailer Vivarte, replaces Lars Olofsson, who had faced mounting criticism over a series of profit warnings that hammered Carrefour shares, down 43 percent over the past year.
"Georges Plassat declared he is well aware of the magnitude of the task ahead, which will require the support of all within the company," Europe's largest retailer said in a statement.
Plassat will join Carrefour on April 2 in the transitional role of chief operating officer, before being appointed CEO at the company's June 18 shareholders meeting, the company said.
The board of Carrefour, which has global sales of over 90 billion euros and 470,000 employees in 32 countries, will consider Plassat's nomination as chairman after the shareholder meeting.
Olofsson's tenure was marred by a string of poor trading results, management defections and strategic U-turns including a failed merger in Brazil, as well as doubts over his flagship plan to revive Carrefour's ailing hypermarkets.
"The appointment of Plassat should be viewed as a big win for Carrefour," said Natalie Berg, director of global research at Planet Retail. "He is a seasoned retail executive with the non-food experience that Carrefour vitally needs."
Plassat spent 14 years at French retailer Casino and two years at Carrefour Spain before joining Vivarte in 2000. He also holds a stake of about 10 percent in Vivarte.
Speculation that Plassat's arrival was imminent had lifted Carrefour shares 8 percent on January 26.
The Frenchman's solid track record in company restructuring won him the backing of Carrefour's biggest shareholder, the Blue Capital holding shared by U.S. private equity fund Colony Capital and Bernard Arnault, France's richest man.
Blue Capital now owns about 16 percent of Carrefour and is sitting on hefty paper losses from the investment, which originated with a 2007 stake purchase for over 40 euros per share. The stock has fallen 24 percent since Olofsson took over in January 2009.
(Reporting by Dominique Vidalon)