In his evening video address released in Kyiv, Zelenskiy said the attacks were intended to show Moscow it would "have to pay for the war with its own losses".
Russian oil industry facilities remain a particular focus of the strikes, he said, as Kyiv seeks to reduce Moscow's energy export revenues, which are considered crucial to financing Russia's war economy.
It comes as Anne Keast-Butler, head of the UK's intelligence agency GCHQ, asserted that Russian President Vladimir "Putin is going backwards on the battlefield".
New data shows "almost half a million Russian soldiers have now been killed since the conflict began," she added.
Zelenskiy's announcement on Wednesday night, local time, came after he urged US President Donald Trump to help Ukraine with air defence systems and interceptors, saying ballistic missiles remain Moscow's "last major advantage on the battlefield".
"I ask for your help in protecting Ukraine's skies from Russian missiles. We have already proposed that Ukraine is ready to purchase the number of Patriot systems and interceptor missiles we need," Zelenskiy said in a letter to Trump and the US Congress, seen by Reuters.
Ukraine's only means to shoot down Russian ballistic missiles is US-made interceptors for the Patriot air defence system. Throughout four years of war, Kyiv has been short of interceptors, but the Iran war has threatened to make resources even more scarce.
Since Trump took office, Ukraine has been purchasing Patriot missiles through NATO's Prioritised Ukraine Requirements List (PURL) initiative, financed by its European allies.
"But the current pace of deliveries through the PURL program is no longer keeping up with the reality of the threat we face," Zelenskiy said in his letter.
"For us - for a nation fighting for its survival - there is hardly anything more painful to see than Patriot batteries with no missiles loaded," he added.
In his nightly video address, Zelenskiy noted it was rare for a foreign leader to address a letter simultaneously to the US president and Congress, "but the current situation requires action, swift and effective action".
"It is important that America hears Ukraine," he said.
Zelenskiy said ensuring Ukraine's protection from Russian ballistic missiles was critical to negotiating peace.
"The sooner we can provide greater protection against ballistic missiles, the faster we can ensure that diplomacy works," he said.
"As long as Russia relies on missiles, its interest in diplomacy is not genuine. We must correct this and we can only correct it together, with America."
The letter was first reported by Ukrainian media outlet The Kyiv Independent. Russia used 30 ballistic missiles against Ukraine in its latest massive strike on Sunday, and only 11 of them were shot down, according to Ukraine's air force.
In the letter, the Ukrainian leader outlined Ukraine's success in fending off Russia's full-scale aggression, now well into its fifth year, and expressed gratitude for US support.
"But as long as Putin still has even one meaningful advantage in conventional weapons, he will avoid conventional diplomacy. Today, his ballistic missiles remain exactly that - his last major advantage on the battlefield," Zelenskiy added.
Meanwhile, Russian lawmakers have backed a draft bill to have bank employees join the fight against Ukraine's long-range drones, with trained bank staff shooting down the unmanned aircraft.
The ambitious plan approved by the nation's lower house of parliament on Tuesday envisages banks installing electronic jamming systems on their premises while selected employees would be trained to shoot down incoming drones.
The bill, which state news agency Interfax said was first presented last August and later expanded in scope, must still be approved by the upper house Federation Council and signed by Putin before coming into force.
With Reuters and AP
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