Merchant M. Mahoney, CBE (died May 4, 1946) was a Canadian diplomat who served as Canada's unofficial representative to the United States and High Commissioner to Ireland.
When the War Mission was wound down in 1921, Mahoney was appointed Canada's agent to the United States of America, pending further arrangements.
As agent, he was provided with an office within the British Embassy in Washington D. C., but had no official status.
In 1927, when the Canadian Legation was established, Mahoney was appointed Commercial Secretary.
Mahoney was appointed Canada's High Commissioner to Éire (Ireland) in 1945, but died a year later in Dublin.