President Barack Obama may make the announcement as early as Tuesday, the report said.
The 61-year-old Locke's grandfather and father, who were both born in China, emigrated to the United States. Prior to becoming Commerce Secretary, Locke was governor of Washington state for two terms.
The Journal said Ambassador Huntsman, formerly a Republican governor of Utah, will leave China next month and may consider running for U.S. president in 2012.
As commerce secretary, Locke has been mostly involved in promoting administration efforts to double U.S. exports by 2014. He has led a number of U.S. business delegations overseas.
Obama has been under pressure from the U.S. business community to appoint someone with business experience at the helm of the Commerce, the report said, noting Locke has no business experience of his own.
The Financial Times, which also reported Locke's pending appointment as ambassador, said U.S. issues with China include the latter's currency valuation, U.S. business access to Chinese markets and protection of intellectual property rights.