Australia says it will create the world's largest network of marine parks ahead of the Rio+20 summit.
The reserves will cover 3.1 million sq km of ocean, including the Coral Sea.
Restrictions will be placed on fishing and oil and gas exploration in the protected zone covering more than a third of Australia's waters.
Environment Minister Tony Burke, who made the announcement, will attend the earth summit in Brazil next week with Prime Minister Julia Gillard.
"It's time for the world to turn a corner on protection of our oceans," Mr Burke said. "And Australia today is leading that next step."
Australia has timed its announcement to coincide with the run-up to the Rio+20 Earth Summit - a global gathering of leaders from more than 130 nations to discuss protecting key parts of the environment, including the ocean, says the BBC's Duncan Kennedy.
The plans, which have been years in the making, will proceed after a final consultation process.
Last year, the Australian government announced plans to protect the marine life in the Coral Sea - an area of nearly 1 million sq km.
The sea - off the Queensland coast in northeastern Australia - is home to sharks and tuna, isolated tropical reefs and deep sea canyons. It is also the resting place of three US navy ships sunk in the Battle of the Coral Sea in 1942.
The network of marine reserve will also include the Great Barrier Reef, a Unesco World Heritage site.
The plan will see the numbers of marine reserves off the Australian coast increased from 27 to 60.
"What we've done is effectively create a national parks estate in the ocean,'' Mr Burke told Australian media.
However, activists and environmental protection groups are likely to be less than satisfied with the plans, having called for a complete ban on commercial fishing in the Coral Sea.
The fishing industry is set to receive hundreds of millions of dollars in compensation, reports say.
Some have also noted that oil and gas exploration continue to be allowed near some protected areas, particularly off western Australia.
The Australian Conservation Foundation said that although the plan didn't go as far as they would like, it was a major achievement in terms of ocean conservation.
Currently the world's largest marine reserve is a 545,000-sq-km area established by the UK around the Chagos Islands in the Indian Ocean.