Ukraine's air force said Russia launched dozens of cruise missiles, as well as ballistic and hypersonic ones, and 168 drones, in a massive overnight attack.
The air force said that nearly 90 per cent of the drones and most of the cruise missiles were downed.
It did not specify whether any of the more deadly ballistic missiles were intercepted - having said last week that providing such information was giving Russia cause to celebrate.
Zelenskiy called Thursday's strike one of the most "cynical, calculated, and large-scale" of the four-and-a-half-year war.
The upper floors of a nine-storey residential block were destroyed in Kyiv's Solomianskyi district, where at least eight people were killed, Mayor Vitali Klitschko said.
He declared Friday a day of mourning.
Outside the damaged apartment block, an elderly woman wailed as rescuers carried out the body of her grandson.
She stood sobbing beside his body after he was placed on the ground, before medics came to support her.
Overall, 30 residential buildings, a school, a children's hospital and a kindergarten were among those damaged in Kyiv and the surrounding areas, Zelenskiy said.
Russia's defence ministry said that the country's forces had used air strikes and drones to hit targets in and around Kyiv, including facilities producing drone components, a military depot and a logistics hub.
As Russia has escalated its ballistic strikes in recent months, Zelenskiy has pleaded with allies to replenish Ukraine's stock of Patriot interceptors - the only weapon in its arsenal capable of downing a ballistic missile.
"Each additional missile saves the lives of our people," Zelenskiy said in a social media post, adding that replacement missiles had not been received.
"Unfortunately ... the world's response to such attacks is not always adequate."
Zelenskiy warned that Russia would not seriously negotiate for peace as long as Ukraine had no missile defences to defend its cities.
US-mediated talks to end the war stalled earlier this year as Ukraine refused to yield to Russian demands to cede more territory.
European Union commission president Ursula von der Leyen said on X, in response to Zelenskiy's message, that she was working with member states and partners to provide Ukraine with anti-ballistic capabilities as "the most urgent of priorities".
Ukrainian Prime Minister Sergii Koretskyi said that some food warehouses and the facilities of the Red Cross around Kyiv were damaged in the overnight attack, which lasted nearly nine hours.
In recent weeks, fresh fruit and vegetables have occasionally disappeared from the shelves in some supermarkets in Kyiv as a result of strikes on logistics depots of food retailers.
Ukraine has handed peace proposals to US negotiators Steve Witkoff and Jared Kushner for a plan to end the war, Zelenskiy said this month.
The Kremlin said on Thursday there was no information yet on a possible visit to Moscow by Kushner and Witkoff, who were last in the Russian capital in January and have not yet visited Kyiv.
No date has yet been confirmed for a proposed visit to Ukraine, according to one source familiar with the discussions.
