Monaco were relegated from the French top-flight for the first time in 35 years after losing 2-0 at home to Lyon on the final day of the Ligue 1 season.
Third-bottom going into the game at Stade Louis II, Monaco needed a positive result to stand any chance of avoiding the drop, but fell to second-half goals by Pape Diakhate and Lisandro Lopez.
French champions in 2000 and UEFA Champions League finalists in 2004, Monaco - who sacked coach Guy Lacombe in January and replaced him with Laurent Banide - will play in the second tier next season for the first time since 1977.
Victory ensured Lyon finished third, four points above Paris Saint-Germain, meaning they will enter next season's Champions League in the play-off round.
With Monaco desperate for points and Lyon jaded after a long season of off-pitch turmoil, a cagey first half witnessed just one clear chance, with Jimmy Briand dragging a shot wide at the end of a Lyon counter-attack.
The hosts had to wait until the 53rd minute for their first real sight of goal, but Lyon goalkeeper Hugo Lloris proved himself equal to Chris Malonga's left-footed curler. Lisandro gave Monaco a fright with a shot that grazed the left-hand post, before the goal the home fans dreaded arrived in the 67th minute.
A deflected Kim Kallstrom free-kick arrived at the feet of Maxime Gonalons, and when his shot was beaten away by Monaco goalkeeper Sebastien Chabbert, Diakhate tapped home from six yards.
The fight drained from the Monaco ranks thereafter and Lisandro confirmed their descent to Ligue 2 eight minutes from time when he chested down an Aly Cissokho cross before ramming home his 17th goal of the season.