Putin's unilateral move, to extend over 30 hours, came after US President Donald Trump on Friday said negotiations between Ukraine and Russia are "coming to a head" in his push to end the grinding three-year war.
Putin ordered fighting to stop as of 6pm Moscow time on Saturday until midnight on Sunday night.
"Based on humanitarian considerations ... the Russian side announces an Easter truce. I order a stop to all military activities for this period," Putin told Valery Gerasimov, chief of Russia's general staff, at a televised meeting.
"We assume that Ukraine will follow our example. At the same time, our troops should be prepared to repel possible violations of the truce and provocations by the enemy, any aggressive actions."
The ceasefire was set to cover Easter Sunday, the height of the Christian calendar, which falls on Sunday this year for all Orthodox, Catholic and Protestant Christians.
Shortly after the announcement, about an hour before it was due to take effect, air raid sirens rang out in Kyiv.
Ukraine's President Volodymyr Zelenskiy dismissed the proposal as "yet another attempt by Putin to play with human lives".
As of 45 minutes before the truce was meant to start, Ukrainian planes were repelling Russian air strikes, Zelenskiy said in a post on X.
In a post later on social media platform X, Zelenskiy quoted Ukraine's top commander as saying that Russian assault operations "continue on several frontline sectors, and Russian artillery fire has not subsided".
"Therefore, there is no trust in words coming from Moscow."
He recalled that Russia had last month rejected a US-proposed full 30-day ceasefire and said that if Russia agreed to "truly engage in a format of full and unconditional silence, Ukraine will act accordingly - mirroring Russia's actions".
"If a complete ceasefire truly takes hold, Ukraine proposes extending it beyond the Easter day of April 20," Zelenskiy wrote.
The head of Ukraine's Centre for Countering Disinformation said Russian forces continued to fire on Ukrainian positions after the truce order was meant to take effect.
The governor of Kherson province Oleksandr Prokudin in southern Ukraine said Russian air strikes began shortly before the truce was due to start and continued after.
He posted a picture of a damaged building.
"Unfortunately, we are not seeing any sort of calm here. The shelling continues and our civilians are under fire," he wrote on Telegram.
Reuters could not independently verify the situation at the front.
Ukrainian bloggers who cover the war said firing continued along the entire line of contact but public broadcaster Suspilne quoted servicemen on the eastern front as saying the number of Russian attacks had declined.
The Russian defence ministry said its troops had been instructed about the ceasefire and would adhere to it, provided it was "mutually respected" by Ukraine.
"One step closer to peace," senior Kremlin adviser Kirill Dmitriev said in a post on X.
Putin has proclaimed unilateral pauses in fighting in the past with little effect on the battlefield, including a 36-hour proposed truce for Orthodox Christmas in January, 2023, which Ukraine rejected.
Putin told Gerasimov on Saturday that Russia welcomed efforts from the US, China and BRICS countries to find a peaceful settlement to the conflict.
Russia and Ukraine both confirmed a swap of more than 500 prisoners of war on Saturday, mediated by the United Arab Emirates.
Zelenskiy, in a post on Telegram, said 277 Ukrainian service personnel had returned home from Russian captivity.
Russia's Defence Ministry said 246 servicemen had been handed over by Ukraine.
It said a further 31 injured prisoners of war had been handed over to Ukraine and 15 of its own wounded servicemen had also been returned by Ukraine.
All Russian servicemen were now in Belarus, awaiting transfer back home.
Video footage posted by Dmytro Lubinets, Ukraine's parliament commissioner for human rights, showed a gathering of Ukrainian servicemen, many wrapped in the blue and yellow flag of Ukraine in a wooded area alongside several buses.
The men were then seen seated on the edge of a tarmac shouting patriotic slogans.
with AP and DPA
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