The Venezuelan opposition leader said that the prize held profound significance, not only for her country but for the world.
"It reminds the world that democracy is essential to peace," she said via her daughter, Ana Corina Sosa Machado, whose voice cracked when she spoke of her mother.
"And more than anything, what we Venezuelans can offer the world is the lesson forged through this long and difficult journey: that to have a democracy, we must be willing to fight for freedom."
A large portrait of a smiling Machado hung in the Oslo City Hall to represent her.
The audience cheered and clapped when Norwegian Nobel Committee head Joergen Watne Frydnes said during his speech that Machado would be coming to Oslo.
Evoking previous laureates Nelson Mandela and Lech Walesa, he said fighters for democracy were expected "to pursue their aims with a moral purity their opponents never display".
"This is unrealistic. It is unfair," he said.
"No democracy operates in ideal circumstances. Activist leaders must confront and resolve dilemmas that we onlookers are free to ignore. People living under the dictatorship often have to choose between the difficult and the impossible."
The 58-year-old engineer was due to receive the award at Oslo City Hall in the presence of King Harald, in defiance of a decade-long travel ban imposed by authorities in her home country and after spending more than a year in hiding.
But she was unable to reach the Norwegian capital in time for the ceremony.
"I will be in Oslo, I am on my way to Oslo right now," Machado told Nobel Committee leader Joergen Watne Frydnes in an audio recording released by the Norwegian Nobel Institute.
It was unclear where she was calling from.
"We don't know exactly when she will land but sometime in the course of the night," the institute's director, Kristian Berg Harpviken, told Reuters.
"Freedom is conquered every day as long as we are ready to fight for her. This is the reason why the cause of Venezuela transcends our borders," she said in the transcript of her prepared speech.
"A people that chooses to be free not only liberates itself, it contributes to the whole of humanity."
In 2024, Machado was barred from running in the presidential election despite having won the opposition's primary by a landslide.
She went into hiding in August 2024 after authorities expanded arrests of opposition figures following the disputed vote.
The electoral authority and top court declared President Nicolas Maduro the winner but international observers and the opposition say its candidate handily won and the opposition has published ballot box-level tallies as evidence of its victory.
In her speech, Machado said Venezuelans did not realise in time that their country was sliding into what she described as a dictatorship.
"When we understood how fragile our institutions had become, it was already too late," Machado said.
Referring to the late president Hugo Chavez, who was elected in 1999 and held power until his death in 2013, she said: "When the ringleader of a military coup against democracy was elected president, many thought that charisma could substitute the rule of law."
"Since 1999, the regime has dedicated itself to dismantle our democracy."
