Both men laid out their vision for improving the relationship between the federal government and aboriginal people if they become prime minister after this fall's federal election.
Mulcair said an NDP government would usher in "a new era" of nation-to-nation relations with indigenous communities, while Trudeau said a Liberal government would work with aboriginal people to build a "renewed relationship."
The office for Aboriginal Affairs Minister Bernard Valcourt said the minister was not in attendance because he was in New Brunswick attending "important events."
In a news release issued after the opposition leaders spoke to the AFN, Valcourt's office said the government is "taking steps aimed at improving First Nations well-being by enabling them to take full advantage of Canada's economic prosperity.
"Meanwhile, the NDP and Liberals continue to oppose and vote against each of our Government's efforts to improve the lives of Aboriginals, and favour irresponsible spending instead of concrete, achievable, and necessary action," Valcourt's office said.
Repealing legislation passed under Harper
Mulcair vowed to create and chair a cabinet committee "to ensure federal government decisions respect treaty rights, inherent rights and Canada's international obligations." He also vowed to repeal the Anti-Terrorism Act, which his party opposed.
The leader of the Official Opposition reiterated his promise that an NDP government would launch a national public inquiry into missing and murdered aboriginal women within 100 days of taking office.
The Liberal leader addressed the need to overhaul the relationship between First Nations and the federal government, including a promise to bolster funding for aboriginal education and targeting the growing socio-economic gap that exists between aboriginal and non-aboriginal Canadians in areas including employment.
A Liberal government, Trudeau said, would "immediately lift the two per cent cap on funding for First Nations programs."
Trudeau said a Liberal government would also conduct a "full review of the legislation unilaterally imposed on Aboriginal Peoples by the Harper government."
While the Liberals voted to support the Conservative government's Anti-Terrorism Act, Trudeau said a Liberal government would repeal those sections of the legislation that are "cause for concern" to aboriginal people.
Bellegarde calls on Canada to make reconciliation
In the first keynote address to the Assembly of First Nations annual meeting, National Chief Perry Bellegarde said First Nations voters need to make a point of making themselves heard in polling booths across the country.
The time is right, he says, because the Truth and Reconciliation Commission's recent report has captured the attention of Canadians with its description of the residential school legacy as "cultural genocide."
"As thousands of brave people shared their experiences and spoke the truth, Canadians woke up to a chapter of their history that must be forever remembered and never forgotten," Bellegarde told an audience of First Nations leaders from across the country.
This is Bellegarde's first meeting as national chief.
He is also calling on the government to respect traditional territories and honour its legal duty to accommodate First Nations people.
"Reconciliation means nothing less than keeping the promises the government of Canada first made to our people to share and live together," Bellegarde said.
"Reconciliation involves all Canadians ... I believe Canadians want their political leaders to do the right thing."
But Bellegarde said that includes a recognition of First Nations' right to say yes or no to development on their territories.
The AFN national chief has been calling for all federal parties to address indigenous issues in their election platforms.