The United States on Monday congratulated Ukraine's novice new president and said it hoped to work with him to defend the country against rival Russia.
Volodymyr Zelensky, a 41-year-old comic with no political experience, was elected Sunday on promises of change but has generally stood by the Western-oriented course of defeated president Petro Poroshenko.
US State Department spokeswoman Morgan Ortagus said that Zelensky's victory showed Ukraine's "vibrant democracy" after "five years of unrelenting Russian aggression."
"The United States maintains steadfast support for Ukraine's sovereignty and territorial integrity within its international borders and will continue to stand with Ukraine as it undertakes essential reforms," she said in a statement.
"We look forward to working with President-elect Volodymyr Zelensky to advance our two nations' shared goal of a secure, prosperous, democratic and free Ukraine," she said.
Russia has taken a wait-and-watch approach to Zelensky, with the Kremlin saying it was too early for President Vladimir Putin to congratulate him.
Zelensky hailed his victory as a sign to people in post-Soviet nations that "everything is possible," but he also has said he wants better relations with Russia.
The United States has supported Ukraine after Moscow in 2014 seized the Crimean peninsula and as Russia backs an insurgency that has claimed around 13,000 lives.
President Donald Trump has spoken fondly of Putin, but the Washington establishment is adamantly opposed to any loosening of pressure.