The British High Commission in Ottawa, Ontario, is the main diplomatic mission of the United Kingdom in Canada.

It is located at 140 Sussex Drive in Ottawa, across the street from Global Affairs Canada (GAC).

The High Commissioner's position was created in 1928 after the Balfour Declaration of 1926 and was the first such posting for Britain.

The High Commission also represents the British Overseas Territories in Canada.

In 2019, the UK Government announced a new building would be constructed for the High Commission, on property next to Earnscliffe.