Waving both Ukrainian and Russian flags and shouting slogans heard during the anti-government protests in Kiev, the demonstrators urged Russian President Vladimir Putin to pull troops back from a Cold War-style confrontation.
Marchers carried placards reading "Putin, get out of Ukraine" and others comparing Russia's move on Crimea with the Nazi annexation of the Sudetenland as Europe rushed headlong into World War II.
Many of the protesters adopted the chants and slogans of Ukraine's popular uprising that ousted President Viktor Yanukovych last month.
University professor Yelena Orlova, 47, whose sign read "Ukraine is a sovereign state", said she did not expect the rally would change her government's position, but believed it was her duty to speak out.
"I don't agree with the policy of Putin," she told AFP. "I am against the annexation of Crimea. I think Russia should respect the borders of Ukraine."
A huge column of people snaked along a central boulevard with a hotch-potch of flags and hand-written placards.
After the march, the protesters gathered on Prospekt Sakharova, the scene of huge anti-Putin rallies that shook Russia in 2011-12.
"We are patriots and Putin is Russia's enemy," activist Ilya Yashin said from the stage.
"Ukraine is a brotherly nation and we will not allow them (the government) to march us into a fratricidal war."