Regional head Oleh Syniehubov said the boy was fatally injured when the building was hit by a Russian 500-kilogram glide bomb.
"He was freed from under the rubble with severe head injuries and fractures," Syniehubov wrote on social media.
"Doctors performed resuscitation measures for more than half an hour. Unfortunately, it was not possible to save the child."
An apartment building in Kharkiv was damaged and at least 35 people were injured in the attack. (AP PHOTO)
Syniehubov said later that rescuers also retrieved the body of an unidentified man from the debris.
Interior Minister Ihor Klymenko said at least 35 people were injured in the attack and others could still be trapped under the rubble, including a missing 15-year-old boy.
Russia has increasingly used powerful glide bombs to pummel Ukrainian positions along the 1000-kilometre line of contact and strike cities dozens of kilometres from the front line.
Kharkiv, a city of 1.1 million, is about 30 kilometres from the border.
President Volodymyr Zelenskiy has repeatedly urged the United States to allow Ukraine to use long-range American missiles to strike air bases deeper in Russia that are used by aircraft carrying glide bombs.
Washington so far has only allowed some strikes close to the border.
Zelenskiy repeated his request on Thursday, publishing a video showing the ravaged building, at least three of its floors destroyed and the rest of it seriously damaged.
"Partners see what is happening every day," Zelenskiy wrote on Telegram.
"And under these conditions, each of their delayed decisions means at least dozens, if not hundreds of such Russian bombs against Ukraine. Their decisions are the lives of our people. Therefore, we must together stop Russia and do it with all possible force."
Russia struck a nine-story building in Kharkiv with a guided aerial bomb. — Volodymyr Zelenskyy / Володимир Зеленський (@ZelenskyyUa) Tragically, there are casualties, including children, and more people may still be trapped under the rubble. All necessary emergency services are on site.Partners see what happens every day. In these… pic.twitter.com/iVLJ6x5K4ROctober 30, 2024
Early on Thursday, Russia also fired 10 missiles of various types at the Dniester Estuary bridge that connects the northern and southern parts of the Odesa region, Ukraine's air force said, adding that only two of them were intercepted. It didn't say whether the bridge was hit.
Russian forces also sent 43 exploding drones over at least nine Ukrainian regions, the air force said.
It said 17 were shot down, 23 jammed and three flew back to Russian-controlled territories.
The head of Kyiv city administration, Serhii Popko, said debris from some of the drones that were intercepted over the capital fell in the Podil district just north of downtown, causing minor damage.
According to Popko, there was only one day in October in which Kyiv residents did not hear an air alert.
During the month, Kyiv experienced two air alerts per day on average, repelling 20 actual aerial attacks targeting the city.
In the country's east, Russian forces continued their slow but steady assault, trying to capitalise on Ukrainian shortages of manpower and ammunition.
In Moscow, the Defence Ministry reported the capture of the village of Yasna Polyana in the Donetsk region that lies on the way to the well-fortified Ukrainian stronghold of Kurakhove.
Ukraine struck back on Thursday with drone attacks.
Authorities in the Russia-occupied city of Berdyansk on the Sea of Azov reported a drone attack on the port early on Thursday, saying three people were injured.
Russia's Defence Ministry said air defences on Thursday downed 21 Ukrainian drones over several regions and the Black Sea.
