Antoine LeCoultre (1803–1881) came from a Huguenot family that had fled Lizy-sur-Ourcq, near Meaux, for Geneva in the 16th century before settling in the Vallée de Joux, where Pierre LeCoultre's son built the church in 1612 around which the village of Le Sentier grew.
Shortly after inventing a machine to cut watch pinions from steel, he founded a small watchmaking workshop in Le Sentier in 1833. In 1844 he invented the millionometer, the first instrument able to measure to a micron, which allowed watch parts to be made more precisely; it was never patented but was kept in use by the firm for over fifty years and shown at the Paris Exposition of 1900. In 1847 he devised a keyless system to wind and set a watch with the crown, using a small push-piece to switch between functions. At the Great Exhibition in London in 1851 he received a gold medal for his work on precision and mechanisation.
In 1866, when the trade was scattered among hundreds of small workshops, he and his son Elie (1842–1917) founded LeCoultre & Cie, bringing all the crafts of watchmaking under one roof in Le Sentier. By 1870 the manufacture employed about 500 people and was developing partly mechanised methods for complicated movements; by 1900 it had created more than 350 calibres. The company still counts its foundation from 1833.