Mr Morrison said the proposal was "ill-defined" and would create constitutional risk in enshrining an Indigenous voice to parliament and executive government.
"It is not necessary to enshrine the voice in the constitution to deliver constitutional recognition for Indigenous Australians. That enjoys broad support," he told parliament on Wednesday.
"It is wrong to conflate the issues of the voice with constitutional recognition and treat them as inseparable.
"The impact of the voice on the operations of executive government and the parliament are also not known, presenting significant and unknown risks that cannot be easily remedied."
It was just the third time Mr Morrison has spoken in parliament since losing last year's federal election, the other occasions being after the death of the Queen, as well as defending himself from being censured following his multiple ministries scandal.
The former leader said the voice would create unnecessary risks to the operation of government and the executive, and would not succeed in closing the gap between Indigenous and non-Indigenous people.
"Permanently changing the constitution in the way the government proposes will sadly not change the desperate circumstances being experienced in so many Indigenous communities across Australia," he said.
"I understand that that is the hope of the proposal, and hope is a good thing, but hope disappointed will be crushing to the soul. And such disappointment can be reasonably foreseen by proceeding with the government's proposal."
Mr Morrison also took aim at sporting codes and business groups that have come out in publicly supporting the referendum.
"While keenly interested in the NRL's opinion on hip-drop tackles and the six-again rule, I don't think I'll be referring to them for constitutional advice in making my decisions on this matter," he said.
While he was prime minister, Mr Morrison rejected calls to establish a voice to parliament in the constitution, but backed work to set up local and regional voice mechanisms.
A proposal to have the body legislated did not proceed.
Indigenous Labor MP Marion Scrymgour said the voice was not a political campaign, but an extension of advocacy from Aboriginal leaders, and represented a significant step forward.
"This constitution, this birth certificate, which we now seek to amend in such a modest way, was predicated on allowing the participating colonies to complete the project of cancelling out Aboriginal people, which they had already embarked upon," she said.
"Giving our people a real voice now is the least that this country can do to make good the wrong that has existed at the heart of our founding document."
Ms Scrymgour decried opponents of the voice who said the constitutional change would divide the country in race.
"It is disgraceful that people use that as a means to create doubt and division in the hearts and minds of people," she said.
MPs will face another long night of talks on the voice, ahead of a vote next month on the final form the referendum will take.
Parliament is set to vote on the final wording of the referendum question along with the changes to the constitution should the proposal succeed.
The lower house isn't expected to vote on the voice bill until next week when the debate will shift to the Senate.
The bill is expected to be finalised in June ahead of the referendum, which will be held between October and December.
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