Video footage posted by Zelenskiy's office showed him in Sumy, the sixth region he has visited in the past week as expectations of a Ukrainian counter-offensive rise.
Zelenskiy walked with border guard commanders through a deep trench at an undisclosed wooded position in Sumy, closely watched by troops in combat gear.
He also visited the towns of Okhtyrka and Trostianets, which drove back Russian forces who occupied parts of the Sumy region for about a month at the start of Russia's invasion in February last year.
Some of the buildings in the two towns had been badly damaged in fighting, and Ukrainian officials say territories close to the border are still regularly bombarded by Russian artillery and air strikes.
"These days, these weeks, we are celebrating the anniversary of the liberation of our cities and communities in our northern regions," Zelenskiy told a small crowd of soldiers and civilians at the railway station in Trostianets before handing out medals.
He later wrote on the Telegram messaging app: "Our people proved that this occupier will be defeated by us, by our morale, by our Ukrainian character. Our people proved it, our warriors proved it."
The Russian invasion has been bogged down for months in fierce fighting along the eastern front, and Ukraine's ground forces commander said last week that a Ukrainian counterattack could come "very soon".
(Reporting by Max Hunder)
