London's unemployment rate hit 6.6% last month, up from 6.3% in July.
London's rate is still below neighbourining major cities, with Windsor now sitting at 9% and Brantford at 7%.
The provincial rate also increased, from 6.4% to 6.8%.
Overall, Statistics Canada says the economy added 12,000 jobs across the country.
However, the national unemployment rate increased for the first time in six months, jumping to 7%. It had been steady at 6.8% since March.