Australia's consumer watchdog will use its new powers to go after big companies under newly-reappointed chairman Rod Sims.

Mr Sims was appointed chairman of the Australian Competition and Consumer Commission in August 2011 for an initial five-year term, before getting an extension in 2016.

He is the first chairman to get a third term, which will run until August 2022.

ACCC chairman Rod Sims re-appointed. Alex Ellinghausen / Fairfax Media

"I'm looking forward to continuing our very strong enforcement work," Mr Sims said in Canberra on Thursday.

"We've just got higher penalties so we'll certainly be seeking penalties against large companies, north of $100 million, if we can achieve that.