People had been on their way to church to celebrate a religious holiday when the strike took place, the ministry said. Of the 129 counted as wounded in the search and rescue operation, 15 were children and 15 were police officers, Interior Minister Ihor Klymenko said in a Telegram post.
"A Russian missile hit right in the centre of the city, in our Chernihiv. A square, the polytechnic university, a theatre," President Volodymyr Zelenskiy, who was on a working visit to Sweden, posted on Telegram.
"An ordinary Saturday, which Russia turned into a day of pain and loss," he added.
A short video accompanying Zelenskiy's post showed debris scattered across a square in front of the regional drama theatre, where parked cars were heavily damaged. The video also briefly showed a body slumped inside a car.
Ukrainian media reported that a public event featuring drone manufacturers had been taking place inside the theatre at the time of the attack. Both sides in Russia's 18-month-old invasion have widely used drones on the battlefield.
In comments to reporters, Klymenko confirmed only that an unspecified event had been taking place in the building and that Ukraine's domestic security service was investigating the matter.
Chernihiv is a city of leafy boulevards and centuries-old churches about 145 km north of the capital Kyiv.
The roof of the neoclassical theatre was torn off by the strike, which also blew out doors and windows in neighbouring apartment buildings and store fronts.
The streets were stained with blood trails and strewn with scraps from first-aid supplies that had been used to treat the wounded.
Russia has attacked Ukrainian cities far from the frontline with missiles and drones as part of the full-scale invasion it launched in February last year.
Kyiv's air force said early on Saturday the Ukrainian military had shot down 15 out of 17 Iranian-made Shahed drones launched by Moscow in an overnight strike.
Meanwhile, Russia's Defence Ministry said on Saturday it had destroyed a Ukrainian drone in the Belgorod region and jammed another near Moscow. A third struck a military airfield in the Novgorod region, damaging a warplane, it also said.
UN condemns 'heinous' attack
The UN called a "heinous" attack a Russian missile strike on Ukraine's northern city of Chernihiv that killed seven people and wounded more than 100 yesterday, hours after President Vladimir Putin met Moscow's top army commanders."It is heinous to attack the main square of a large city, in the morning, while people are out walking, some going to church to celebrate a religious day for many Ukrainians," said Denise Brown, the UN's humanitarian coordinator for Ukraine.