The host of The Block last month inked a deal to become the federal government's national careers ambassador in a bid to get more young people on the tools.

Mr Morrison said the agreement was commercial in confidence, meaning it couldn't be revealed to the public.

"That's a protection that's provided to individual Australians that their own commercial arrangements aren't exposed," he told 3AW radio on Friday.

He said the government signed similar agreements with suppliers to build road and rail projects.

"There are a lot of companies that do business with the government who seek those commercial-in-confidence agreements," Mr Morrison said.

"It's not a new practice, it's quite a longstanding one."

The Gold Logie-winning Cam is paid by the government to highlight how practical and technical training can lead to high-paying jobs.

Labor and the unions have called for more money to be poured into TAFE instead of celebrity appointments.

Australian Associated Press