One claim is that it was commissioned by lieutenant-governor of Upper Canada John Graves Simcoe and built around 1795 by Augustus Jones.

[2] However, Jones left no account of having built a cabin, and recorded that his surveying team lived in tents.

The building's namesake comes from William Osterhout, a United Empire Loyalist who in 1805 was given the first Crown land grant from King George III as reward for his service with the Butler's Rangers.

[2] The property was later owned by Alexander McDonnell, Duncan Cameron, and John Ewart, although no evidence suggests that they built the cabin.

As part of the 1978 sale of the Guild Inn property, the land around the cabin came under the administration of the Toronto Region Conservation Authority.