The area near Etchemin Lake was first described in 1828 as lovely by the surveyor Emmanuel. A few years later, in 1835, the region sees its first settler, Commissary General Sir Randolph Isham Routh KCB (1782–1858), who was given a land grant of 9,000 acres (36 km2) for his services to the Crown.
Sir Randolph Isham Routh's Lac Etchemin Summer Residence 1838, painted by his second wife, Marie Louise Taschereau (1811–1891)
The new municipality of Lac-Etchemin was created in 2001 following the amalgamation of the city of Lac-Etchemin and the parish of Sainte-Germaine-du-Lac-Etchemin.