Thomas Mayo, a leader of the campaign for constitutional change, said the referendum loss will make it harder for the nation to discuss global human rights breaches.
"It's embarrassing," he told ABC's RN on Tuesday.
"It's hard for Australia to talk about human rights to other countries like China, when we ... still have such marginalised people and still make decisions about them."
Australia would have a hard time holding its "chin up" when it was the only former British colony not to have recognised Indigenous people in its constitution, Mr Mayo said.
"It is very difficult now ... as far as international relations go and human rights, for us to to speak to others about their record when we haven't closed our colonial chapter yet," he said.
Asked if Prime Minister Anthony Albanese should call out racism as a factor behind the majority 'no' vote, Mr Mayo said he didn't believe that would be helpful.
"The important thing, in regards to what Indigenous people want from the prime minister and his government and the parliament, is to now move forward with efforts to close the gap," he said.
Mr Mayo did not sign an open letter sent by Indigenous leaders who supported the voice referendum, which called the 'no' vote a "shameful victory".
"There's a lot of hurt that such a modest proposal was rejected by the Australian people," he said.
The government has said it is waiting to hear feedback from Indigenous people on the next steps forward.
Opposition Leader Peter Dutton has backed away from his pledge to hold a second referendum on constitutional recognition for Indigenous Australians following the defeat.
But he has called for an audit of Indigenous program spending and a royal commission into the alleged sexual abuse of Aboriginal and Torres Strait Islander children.
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