1880 through 1922. He contributed to the development of the modern Jaeger-LeCoultre company, which shares his name.
In 1903, Jaeger met Jacques-David LeCoultre, grandson of Charles Antoine LeCoultre, in Paris. Jaeger and LeCoultre began a life-long collaboration, producing ultra-thin and complicated luxury watches. Indeed, it was Jaeger who challenged LeCoultre to begin producing ultra-thin movements. This collaboration was so successful that Jaeger signed a 14 year exclusivity agreement in 1907 with Cartier agreeing to exclusively supply movements, manufactured by LeCoultre and finished by Jaeger.
During World War I, Jaeger and LeCoultre & Cie partnered to create aviation and automobile dials and controls for the allies. This became a major business for Jaeger, known for automobile gauges throughout the 20th century.
Jaeger, operating from Paris, initially registered his patents in Switzerland through a Basle lawyer but established his own firm in Geneva in 1917. LeCoultre brought him into the administration of his firm around this time, and Jaeger reciprocated.
In failing health, Edmond Jaeger gradually turned control of his firm over to Jacques Lebet. Working in Paris, Lebet oversaw the company's workshops until Jaeger's death in 1922. Lebet replaced Jaeger at his namesake firm, the Geneva operation of which was gradually incorporated into LeCoultre's.
In 1937, LeCoultre's sales operation, based in Lausanne, was renamed “Société de Vente des Produits Jaeger-LeCoultre,” and this operation soon handled Vacheron Constantin's sales as well. The firm of Jaeger-LeCoultre continues to this day as part of the Richemont group.