The JS11 exploited the ground-effect principles pioneered by the Lotus 78 and 79, using venturi tunnels under the car to generate substantial aerodynamic downforce. The aluminium monocoque was paired with the ubiquitous Ford Cosworth DFV V8. The car's fundamental competitive strength was also the source of its greatest weakness: it produced downforce at a level the chassis could not entirely manage, causing the aluminium structure to flex under load, which lifted the sliding skirts and broke the venturi seal, reducing the ground effect. This chassis flex problem, which emerged from the fourth race at Long Beach, hampered the team throughout 1979 despite its strong raw speed.
Jacques Laffite drove the JS11 to victory at the first two rounds of the 1979 season. Patrick Depailler, his teammate, added a further win in Spain, and the team remained in championship contention for much of the year. However, the inherent chassis flex problem prevented the Ligiers from consistently matching the Ferrari of Jody Scheckter and Gilles Villeneuve, and later the all-dominant Williams of Alan Jones. Depailler suffered serious injuries in a hang-gliding accident mid-season and was replaced by Jacky Ickx, who was unable to extract the same performance and left at year's end. Ligier finished third in the 1979 Constructors' Championship.
For 1980 the JS11 was substantially updated, internally designated the JS11/15, with improved aerodynamics and enhanced ground-effect performance. Didier Pironi replaced Depailler alongside Laffite. The chassis flex problems were resolved, but a new issue emerged: the enormous downforce loads were now being transferred directly onto the suspension arms and wheel hubs, causing stress fractures under hard braking. Suspension and tyre failures through the mid-season cost the team several certain victories.
Despite these setbacks the team posted two race wins and finished second in the 1980 Constructors' Championship, ahead of Brabham BT49. The Brabham and the Williams FW07 were the dominant cars that year, and Alan Jones took the Drivers' title, but the Ligier was undeniably competitive. The JS11/15 was subsequently used as a primary test bed for Michelin's tyre development work.
To mitigate the downforce overload, Ducarouge devised a solution called the "clapet" — French for "valve" — consisting of a series of flaps inside the venturi tunnels that would open to release pressure beyond a set threshold. Because the system constituted a movable aerodynamic device, the team closely guarded its existence as a secret. Technical illustrator Giorgio Piola discovered and photographed the clapet at the final race of the 1980 season at Watkins Glen, while one of the two Ligier entries was being repaired after an accident.
The JS11 appeared in the animated television series Transformers as the alternate mode of the Autobot character Mirage. Restrictions on tobacco advertising in various markets led to the "Gitanes" sponsor logo being renamed "Citanes" in that context.
The JS11 represented Ligier's finest era in Formula One. Its evolution into the JS17 for 1981 continued the team's V12 programme under a Talbot-Matra banner. The car's five wins and seven pole positions remain the high-water mark of French constructor achievement in the world championship to that point.