"It powerfully demonstrates... the region's strong commitment to opening up markets in the face of this crisis," Crean said.
"It's the most comprehensive FTA [free trade agreement] that Asean has ever signed and the largest FTA that Australia and New Zealand have ever signed in terms of two-way trade."
"This will keep trade flows open in the region, increase growth and give a much-needed boost to confidence."
The region is heavily dependent on exports and has seen a significant fall in trade in the worldwide economic downturn.
The nations hope the agreement, which they started outlining in 2005, will come into play before the start of next year.
The Asean nations have a combined GDP worth over $2 trillion, according to the Singaporean government.
Asean plans to establish a single market and manufacturing base by 2015 in a bid to remain competitive, especially with the rise of India and China.
Meanwhile, Asean foreign ministers have failed to agree on a new human rights body, putting the brakes on plans for political integration of the 10-member bloc.
Plans for leaders to meet with delegates from civil society and non-governmental organisations suffered a setback on Saturday when Cambodia and Myanmar refused to recognise groups representing their countries.
Member nations signed the charter in 2007 to promote democracy and regional security, alleviate poverty, fight crime and create a single, competitive market with free flow of capital.
Despite frequent criticism of Asean's non-intervention policy and its lack of action on human rights, Surin Pitsuwan, its secretary-general, insisted Asean was committed to moving forward.
"A new Asean means an Asean living under the rules of law among ourselves," Surin told reporters on Friday.