Zelensky visited the front line in the Kharkiv region.
The president of Ukraine has made a rare trip outside the capital, Kiev, says the presidential office.
According to media reports, Zelensky visited front-line positions in the Kharkiv region.
“I want to thank each of you for your service. “You risk your life for all of us and our state,” the president told troops.
The northeastern city has experienced some of the fiercest fighting since Russia launched its aggression on Ukraine on February 24.
His visit comes at a time when Ukraine has begun receiving Harpoon anti-ship missiles from Denmark and others from the US.
Ukrainian Defense Minister Oleksii Reznikov was quoted as saying that supplies of Harpoon missiles were the result of co-operation between several countries.
Ukraine has demanded more sophisticated weapons, but so far most of the aid has been in short-range systems, such as anti-tank weapons.
Meanwhile, the US is reportedly considering a request from Ukraine to supply Kiev with heavier, longer-range weapons, but has not yet made a final decision.