The Municipality of Leslie was incorporated in 1860 as a part of Thorne, under the mayorship of James Martin. Seven years later the township broke away and was joined with Clapham, with George Palmer as mayor. In 1876 Huddersfield joined the other two, with the first mayor of the united townships being Francis Pelletier.
The principal village in the municipality, Otter Lake began as a depot for the Philemon Wright Lumbering Company. Located on 500 acres of white pine bush overlooking Farm Lake, the depot had a post office, store and blacksmith shop, as well as several shanties.
Logging and pulpwood activities still play an important role in the area's economy, as does tourism, with a number of beautiful cottage situated on the many lakes in the area, such Hughes, Leslie, Clarke, McCuaig, and Otter Lake.
Leslie Lake, located 10 km from the village, is the site of a one-time provincial park that is now owned by the municipality. Leslie Park offers camping sites and nature trails as well as an excellent beach with boat rentals.
The oldest church in Otter Lake is St James Anglican, built in 1865. The first Catholic church in the community was moved into the village from Thorne in 1882. In 1914 it was replaced with St Charles Borromeo, a stone church that burned in 1982, and was replaced soon after with a modern structure.