"I want to thank you from the people of Ukraine, from our state for the great work you are doing, for your impeccable service."
Mykolaiv is a key target for Russia as it lies on the way to the strategic Black Sea port of Odessa. It is around 100 kilometres (62 miles) northwest of Kherson, which fell to Russia in the first weeks of the war.
Zelensky surveyed the badly damaged regional administration building in Mykolaiv and met officials in what appeared to be a basement where he handed out awards to soldiers, in a video released by his office.
Soldiers in Mykolaiv meanwhile are trying to keep their pre-war routines alive, with one saying he will not give up his vegan diet on the frontlines.
Oleksandr Zhuhan said he had received a package from a network of volunteers to keep up his plant-based diet.
"There was pate and vegan sausages, hummus, soya milk... and all this for free," the 37-year-old drama teacher said happily.
Back in Kyiv, with shockwaves from the war continuing to reverberate around the world, thousands gathered to pay tribute to one young man -- Roman Ratushny, a leading figure in Ukraine's pro-European Maidan movement, who was killed fighting Russians in the country's east earlier this month aged just 24.
In front of the coffin draped in a yellow and blue Ukrainian flag at the foot of a monument that overlooks the sprawling Independence Square in the capital, people of all ages saluted his memory.
"I think it is important to be here because he is a hero of Ukraine and we must remember him," Dmytro Ostrovsky, a 17-year-old high school student, told AFP.
The loss put a human face on the shared grief of Ukrainians, as the bloodshed continues.
The worst of the fighting continues to be in the eastern industrial Donbas region, with battles raging in villages outside the city of Severodonetsk, which Russia has been trying to seize for weeks.
"There's an expression: prepare for the worst and the best will come by itself," the governor of the eastern Lugansk region, Sergiy Gaiday, told AFP in an interview Ukrainian-controlled city across the river from Severodonetsk.
"Of course, we need to prepare."
Wearing a flak jacket and carrying gun cartridges and a tourniquet, he said Russian forces "are just shelling our troop positions 24 hours a day."
Earlier, Gaiday said on Telegram that there was "more destruction" at the besieged Azot chemical plant in Severodonetsk, where hundreds of civilians are sheltering.
He also said Lysychansk is being "heavily shelled".
In Lysychansk, there are signs of preparations for street fighting: soldiers digging in, putting up barbed wire and police placing burnt-out vehicles sideways across roads to slow traffic, as residents were preparing to be evacuated.
"We're abandoning everything and going. No one can survive such a strike," said history teacher Alla Bor, waiting with her son-in-law Volodymyr and 14-year-old grandson.
Meanwhile, pro-Russian officials in the eastern, separatist-held city of Donetsk said five civilians were killed and 12 injured by Ukrainian bombardment.
And Russian state television aired social media videos of two US military veterans who went missing last week while fighting alongside the Ukrainian army, stating they had been captured by Russian forces.
US president Joe Biden had said on Friday he did not know the whereabouts of Alexander Drueke and Andy Huynh, after their relatives lost contact with the pair. A third American is also missing.
In Lysychansk, the governor Gaiday admitted that watching his home city, Severodonetsk, be shelled and people he knew dying was "painful."
"It's all painful, I'm a human being but I bury this deep inside me," he said, adding that his task is to "help people as much as possible".