According to the prosecutor, around 200-300 war crimes are committed every day. Iryna Venediktova said more than 500 suspects have been identified, which include Russian ministers, military commanders and propagandists.
Prosecutions have begun against about 80 of them.
Ms Venediktova told a news conference in the Hague that “about 200-300 war crimes are committed every day”.
A few thousand alleged war crimes have been reported in the eastern Donbas region, where fierce fighting is taking place between Ukrainian and Russian troops.
Ms Venediktova said that although Ukrainian authorities did not have access to the Russian-held areas of Donbas, they were interviewing evacuees and prisoners of war.
Prosecutors are investigating claims of people being tortured, civilians being killed and civilian infrastructure being destroyed, Ms Venediktova said.
Other allegations have been made about Ukrainian children and adults being forcibly taken to Russia, she said.
Russian forces have previously been accused of killing civilians in Bucha and other Kyiv suburbs, as well as repeated assaults on civilian infrastructure, which include hospitals and a theatre in Mariupol that was sheltering hundreds of civilians.
On Tuesday, a Ukrainian court convicted two Russian soldiers of war crimes for the shelling of civilian buildings.
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It comes as Ukraine civilians fear for their lives in the eastern region of Luhansk, where Russians are fighting to take control of Severodonetsk, one of the last remaining cities held by Ukraine.
Three more European countries — Latvia, Estonia and Slovakia — meanwhile joined an international investigation team probing war crimes in Ukraine on Tuesday.
Prosecutors from Poland, Lithuania and from the Hague-based International Criminal Court are already part of the team.