Greens media spokesperson Senator Sarah Hanson-Young slammed the current media environment, saying "we have one of the most concentrated media markets in the democratic world".
"The rules have put profits ahead of the public interest ... We are going to shine a light on the concentration of our news media with a Productivity Commission Inquiry," she said.
"We can strengthen our democracy by halting the slide toward more and more concentrated news ownership."
Senator Sarah Hanson-Young
The rules have put profits ahead of the public interest
The party would also implement a new "public interest test", as recommended by the 2012 Convergence Review and the ACCC, which would "apply to changes in control of nationally significant media enterprises".
The test would see if changes in control would impact editorial independence or "diminish the diversity of unique owners".
"This would help ensure that future sales and mergers of media organisations are in the public interest, not just the interest of multinational companies or wealthy individuals wanting to wield influence over public debate," the Greens policy says.
Since being elected, the Coalition has significantly loosened the country's media ownership laws.
The government scrapped the "two out of three" rule, which prevented one company from owning print, radio and television assets in the one city.
It also abolished the "reach rule" which prevented a one TV broadcaster reaching more than 75 per cent of the population.
Social media regulation
Additionally, the Greens want to commission an inquiry into digital platforms and social media to "stop the spread of misinformation and hate".
"With the concentration of power in the hands of a few, and virtually no rules to govern what they do with this power, it's clearly time to have a public debate about the role and regulation of the digital space," policy material says.
This inquiry would look into "the role of digital and social media platforms in upholding the rights and protections of their users, and contributing to public discourse" and "the role of public interest in setting standards for the digital age".
Senator Hanson-Young said "Australians from all walks of life are concerned about the role the news and social media are playing in people's lives".
"In an era of 'fake news', tragedies like we saw in Christchurch, and countless examples like the treatment of Tayla Harris, it's easy to see why."
The party would also introduce tax breaks for some news subscriptions and donations.