But charges will not be dropped unless protesters vacate government buildings and clear a barricade in Kiev, the authorities warned.
Many of the freed detainees will remain under house arrest.
After the releases, the opposition said it would comply with some of the government's demands.
The detainees were released under an amnesty passed last month to defuse an increasingly violent stand-off.
Ukraine has been gripped by demonstrations since President Viktor Yanukovych abandoned plans to sign a far-ranging association agreement with the EU in November.
Instead, he advocated closer trade relations with Russia, which dominated Ukraine for centuries until the fall of the Soviet Union in 1991.
Dmytro Poltavets was the last jailed demonstrator to be released, according to the Headquarters of National Resistance, which unites Ukraine's three leading opposition parties.
He had been detained on 23 January on Hrushevskyy Street in central Kiev, the scene of clashes with riot police, on a charge of joining in mass disturbances.
Prosecutor-General Viktor Pshonka said that if protesters met the conditions of the amnesty by Monday, all criminal cases against the detainees would be closed within a month.
The conditions include vacating Kiev city hall and other buildings, and clearing barricades on Hrushevskyy Street.
In a statement, the opposition movement said it would partially re-open the street to traffic.
"The idea is that the protesters will be there, and will control this street..." activist Andriy Dzyndzia said.
"We will not free it fully."
Some protesters would also remain on guard at the city hall, he added.
A new mass protest rally has been called for Sunday, on the capital's Independence Square.
Source: BBC News