The war, which has been raging in the country for almost 100 days, has also seen almost 450 children injured, while others are missing.
Mr Zelensky said: “During the 98 days of the Russian invasion, 689 children were injured as a result of the occupiers’ attacks. And these are only those we know about. We do not yet have all the information from the territory that is currently occupied.
"But from what is known today, 446 children were injured, 243 children died and 139 went missing.”
He added: “Eternal memory to everyone whose life was taken away by the Russian war against us against Ukrainians, against Ukraine.”
President Zelensky also said 200,000 children were among the Ukrainians who had been forcefully taken to Russia. The number includes children from orphanages, children taken with their parents and those separated from their families.
He said: “The purpose of this criminal policy is not just to steal people, but to make those who are deported forget about Ukraine and unable to return.”
In a video address to the Luxembourg Parliament on Thursday morning, Mr Zelensky said he believed Ukraine had already become a “de facto member of the EU”.
“I believe that Ukraine is already showing by its actions that it meets the European criteria,” he said.
Meanwhile, officials said Russian cruise missiles had struck and “severely damaged” railway infrastructure around the western Ukrainian city of Lviv.
Lviv regional governor Maksym Kozytsky said five people were wounded in the strike.
Anton Gerashchenko, an adviser to the country’s interior minister, said the Russians hit the Beskidy railway tunnel in the Carpathian Mountains in an apparent effort to cut a key railway link and disrupt shipments of weapons and fuel.
However, the head of Ukrainian railways said the damage to the railway was still being assessed, but the tunnel was spared.
The strike reportedly delayed three passenger trains, but all later resumed their journeys.
Ukraine’s emergency officials said Russian shelling overnight also set a school on fire in the city of Kharkiv, with a woman dying in the blaze.
Another man sustained injuries. Fires from the shelling also occurred in other areas of the Kharkiv region.
Russian forces also shelled the Dnipropetrovsk region overnight, its governor Valentyn Reznichenko said on Telegram.
He said the shelling took place on the border with the Kherson region, much of which is under Moscow’s control.
In the Sumy region that borders Russia, three people were wounded as a result of overnight missile strikes, governor Dmytro Zhyvytskyi said.
In the east, according to Ukraine’s General Staff, Russian troops continued storming the key city of Sievierodonetsk.
Moscow’s forces also stormed the town of Komyshuvakha in the south-eastern Zaporizhzhia region, large parts of which are under Russian control, the General Staff’s morning update said.
Germany’s vice chancellor meanwhile said Russia’s continued income from high fuel prices “hurts”, but insisted “time is working against Russia” with its economy collapsing.
Robert Habeck, who is also Germany’s economy minister, told the German parliament “the income that Putin has obtained in recent months because of high prices hurts, and we can only be ashamed that we haven’t yet managed to reduce this dependence more significantly”.