The Ottawa River timber trade, also known as the Ottawa Valley timber trade or Ottawa River lumber trade, was the nineteenth century production of wood products by Canada on areas of the Ottawa River and the regions of the Ottawa Valley and western Quebec, destined for British and American markets. It was the major industry of the historical colonies of Upper Canada and Lower Canada and it created an entrepreneur known as a lumber baron. The trade in squared timber and later sawed lumber led to population growth and prosperity to communities in the Ottawa Valley, especially the city of Bytown. The product was chiefly red and white pine.The Ottawa River being conveniently located with access via the St. Lawrence River, was a valuable region due to its great pine forests surpassing any others nearby. The industry lasted until around 1900 as both markets and supplies decreased, it was then reoriented to the production of wood pulp which continued until the late 1990s and early 2000s.

The Ottawa River is a river in the Canadian provinces of Ontario and Quebec. It is named after the Algonquin word 'to trade', as it was the major trade route of Eastern Canada at the time. For most of its length, it defines the border between these two provinces. It is a major tributary of the St. Lawrence River and the longest river in Quebec.