The longest-ever serving chairman of the Australian Competition and Consumer Commission is due to step down in March after a long tenure marked by regulatory battles with some of the world's biggest companies.

Mr Sims says he will use the change of pace to spend more time on pet policy projects.

"I'm a pretty dull character," says Mr Sims, who recently stared down Facebook and Google over a code that prompted the tech giants to strike revenue-sharing deals with many media outlets.

"I want to think and write on public policy that interests me."

Mr Sims' decade-long role as ACCC chairman has been recognised in the 2022 Australia Day Honours List; he has been appointed an Officer (AO) of the Order of Australia for his service to public administration in economic policy and regulatory roles.

The 71-year-old is best known as an activist regulator; a term he doesn't shy away from.

"I firmly believe that if the ACCC is not going to be the champion for competition, who is?

"If we see things that are anti-competitive, we need to call it out."

The competition watchdog has, under his tenure, engaged in high-profile actions that have become talking points for the general public.

In 2013 and 2014, the ACCC pursued supermarket giants Coles and Woolworths to limit the size and scope of "shopper dockets" - that rewarded customers with fuel discounts - over concerns smaller businesses would suffer.

German car maker Volkswagen was penalised $125 million in 2019 for misleading customers and violating emission standards, representing the largest ever fine imposed on a company for breaching Australian consumer law.

Last year, Telstra was ordered to pay $50 million for signing up more than 100 Indigenous Australians for cell phone contracts they didn't understand and couldn't afford.

Mr Sims, from Melbourne, says when he took over as ACCC chairman in 2011, the regulator would have been content to extract million-dollar fines through court action. One of his legacies is that there are far bigger fines on the table for breaches of consumer law.

"The companies have come to see there's some pain in breaching consumer law," he says.

"It really transforms corporate Australia's approach to consumer law and that can only be good for consumers."

The outgoing competition boss says there is still work left undone, including a proposed overhaul of Australia's merger laws, which he says currently do not adequately protect competition.

He says the timing hasn't been right to pursue those changes given the COVID-19 pandemic has required so much attention from government officials.

"People have generally underestimated the toll on government ministers and bureaucrats the pandemic has taken," Mr Sims says.

It's an area of reform he plans to keep working on and advocating for after he steps down from the ACCC, while eschewing more flashy endeavours.

Mr Sims enjoys watching opera and sport - most notably he is a long-term supporter of the Hawthorn Football Club - but he says he won't be pursuing a role in sports administration as this would only ruin a treasured hobby.

Australian Associated Press