The neighbourhood began as a small village in the 1850s, which grew up around the Toronto Nurseries owned by George Leslie and sons, after whom the community is named. Most of Leslieville's residents were gardeners or were employed at one of the brick-making factories in the area.
Alexander Muir, the composer of The Maple Leaf Forever, was the first principal of the Leslieville Public School, one of the first buildings in the village. Muir was inspired when a brilliant maple leaf fell on his jacket from a Leslieville tree. That tree is still standing today and has become a famous landmark in the community.