Following a pattern of heavy aerial bombardment at times of Ukrainian battlefield or diplomatic advances, Russia launched 32 missiles in the early hours, Ukraine's Air Force said.
Half were shot down, it added, a lower rate than normal.
Among them, air defences in the south downed eight Kalibr missiles fired from a ship in the Black Sea, Ukrainian officials said. Other missiles struck northern and western Ukraine as well as the central regions of Dnipropetrovsk and Kirovohrad.
Russia has usually carried out its biggest waves of air strikes in daylight, striking energy facilities, but Ukrainian officials suggest Moscow is starting to adapt strategy, including using air balloons for reconnaissance.
"The Russians have changed their tactics somewhat. They conduct active reconnaissance, use false targets," Andriy Yermak, head of the Ukrainian presidential staff, wrote on the Telegram messaging app.
Ukraine did not say why fewer missiles had been knocked out than usual but it has previously reported lower success rates when Russia fired Soviet-era Kh-22 missiles.
Bolstered by tens of thousands of reservists, Russia has intensified ground attacks across southern and eastern Ukraine in recent weeks, and a major new offensive appears to be shaping as the first anniversary of its Feb. 24 invasion nears.
The conflict has killed tens of thousands of people, pulverised Ukrainian cities, destabilised the global economy just as it was recovering from the Covid pandemic, and uprooted millions of people from their homes.
Showing the scale of the humanitarian disaster, Germany said 1.1 million people arrived from Ukraine in 2022, exceeding an unprecedented migrant influx in 2015-16.
Russia did not immediately comment on the overnight bombardment, though on Wednesday it was touting Ukrainian retreats in parts of the eastern province of Luhansk.
Luhansk and Donetsk provinces make up the Donbas, Ukraine's industrial heartland, which is now partially occupied by Russia. It wants full control of the Donbas and its current focus is on encircling and taking the small city of Bakhmut in Donetsk.
'Towards victory': Zelenskiy
Bakhmut's capture would give Russia a stepping stone to advance on two bigger cities, Kramatorsk and Sloviansk further west in Donetsk, to revive Moscow's momentum ahead of the Feb. 24 anniversary.
Trying to counter that, NATO alliance nations are ramping up production of artillery munitions in efforts to keep pace with Ukraine's rapid use of them.
Ukraine has received many billions of dollars in military aid, particularly from the United States which has committed more than $27.4 billion since the conflict began.
Senior U.S. officials have advised Ukraine to hold off with a major counter-offensive until the latest supply of U.S. weaponry is in place and training has been provided.
"We have to ensure that this spring it is truly felt that Ukraine is moving towards victory," President Volodymyr Zelenskiy said.
He thanked Norway for pledging $7 billion over five years, its largest aid programme ever for a single recipient nation.
Russia calls the invasion a "special military operation" against security threats and has cast deliveries of heavy weapons to Ukraine as proof that the West is escalating the war.
Kyiv and its allies call Russia's actions a land grab.
In the latest of a stream of foreign dignitaries to visit Ukraine, Israeli Foreign Minister Eli Cohen was set to meet Zelenskiy in Kyiv. It was the first such visit from a senior Israeli official since the war began.
Israel, which coordinates with Russia over strikes on suspected Iranian targets in Syria, has stopped short of pledging any direct weapons supplies to Kyiv.
Belarus, which allowed Russia to use its territory to send troops into Ukraine at the start of the war, said it would only fight alongside its ally if it was attacked.
Its President Alexander Lukashenko has repeatedly denied suggestions from Kyiv that it could join in the conflict.