But the victory has been clouded by questions over how Gadhafi was killed after images emerged showing he was found alive and taunted and beaten by his captors.
The long-awaited declaration of liberation will come more than two months after revolutionary forces swept into Tripoli and seized control of most of the oil-rich North African nation. It was stalled by fierce resistance by Gadhafi loyalists in his hometown of Sirte, Bani Walid and pockets in the south.
Sirte was the last to fall, but Gadhafi's son and one-time heir apparent and many of his fighters have apparently escaped, raising fears they could continue to stir up trouble.
With Gadhafi gone, however, the governing National Transitional Council was moving forward with efforts to transform the country that was ruled by one man for more than four decades into a democracy.
In Tripoli, residents said they were relieved Gadhafi was killed, not captured, allowing the nation to move forward without fear that his supporters would try to sabotage the transition to democracy.
"If there was a trial, it would take some time ... Maybe there would be revenge attacks," said Hosni Bashir, an employee in Libya's national oil company, who was attending the first meeting of a new political party in a Tripoli hotel. "Now, they (Libya's new leaders) can start."
Initially, NTC officials said the declaration of liberation would be made Saturday in the eastern city of Benghazi, the revolution's birthplace. But spokesman Abdel-Rahman Busin said preparations were under way for a Sunday ceremony instead. He didn't give an explanation for the delay.