Lyon's Juninho Pernambucano scored the only goal of the game against Sedan at the Gerland Stadium on Wednesday to set up a French Cup final against Paris Saint Germain at the Stade de France later this month.
Juninho found the net two minutes before time to keep the league leaders on course for a first-ever league and cup double should they beat Bordeaux to the league title then have a victory over PSG on May 24.
Lyon last won the French Cup way back in 1973.
PSG had beaten second-division Amiens by the same score in the other semi-final on Tuesday.
Lyon managed to win with a workmanlike, rather than an elegant, performance though they left it late when Juninho, who had replaced Kim Kallstrom after 70 minutes, scored from a long-range free-kick after a foul by Albert Baning.
Organized Sedan had chances through Alexis Allard in the first half, but both his shot and header were stopped by Lyon keeper Gregory Coupet, and he had another chance well into the second half.
Lyon had most of the goal opportunities however, through Mathieu Bodmer, Kader Keita, Fabio Grosso and Hatem Ben Arfa, though Sedan keeper Patrick Regnault held firm.
Juninho’s late goal meant Lyon qualified for their second final in two years after losing to Bordeaux 1-0 in the League Cup final.