Wrapped in Ukrainian and EU flags, some with their children hitched on their shoulders, the protesters waved lamps or cellphones as they sang the national anthem when the clock struck midnight on the square, known locally as Maidan.
"Maidan is the place to be for New Year's. The most important things happened here this year," said Volodymyr Drumashine, a beekeeper who travelled to Kiev from Tcherkassy, 120 miles south of the capital.
The square has been the headquarters of the protest movement since Yanukovych refused to sign an agreement bringing Ukraine closer to the EU in late November, sparking further anger when he accepted a bail-out from Russia.
Protesters have set up camp on the square and erected barricades to prevent security forces from entering the area.
The protests are the biggest to hit Ukraine since the 2004 Orange Revolution, a popular uprising which forced the annulment of fraudulent elections initially claimed by Yanukovych.
"This year, I couldn't just stay at home watching television which turns us into zombies," said Olena Turovska, 26.
"Everything is different today, the country has changed."
Jailed ex-Prime Minister Yulia Tymoshenko, whose detention supporters say is aimed at eliminating her from politics, had a message for the revellers in a letter read out by one of her allies.
"In 2014, the country will start to rid itself of dictatorship. This will be a year for free Ukrainians," she said, adding that the protest movement was "the main success of the year – and the decade."
"I know that one day we will sing the national anthem together on Maidan."
Yanukovych admitted in a message to the nation that 2013 had been "the most difficult year in the history of Ukraine" since its independence in 1991.
Source: The Telegraph