ABC News' Will Steakin estimates that Zelenskyy, who has broad bipartisan support on the Hill, received 18 standing ovations during his speech.

Republican Minority Leader Kevin McCarthy, the likely next House speaker, stood and clapped along with other lawmakers at nearly every interval.

Some other Republicans, including Reps. Jim Jordan, Andrew Clyde, Matt Gaetz and Lauren Boebert, stood for less than half of the ovations but were seen repeatedly clapping as well.

Gaetz appeared to be on his phone through the speech. At one point he showed Boebert something with a smile

Gaetz has been critical of future Ukrainian aid while McCarthy has called for Republicans to ensure accountability on how it is used.

-ABC News' Adam Carlson

Closing his speech, Zelenskyy quoted late President Franklin D. Roosevelt and gifted a battle flag signed by soldiers to Congress as lawmakers debate additional funding to Ukraine.

"'The American people, in their might, will win to absolute victory.' The Ukrainian people will win too, absolutely," he said to applause.

"I know that everything depends on us, on Ukrainian armed forces, yet so much depends on the world. So much in the world depends on you," he told lawmakers. "When I was in Bakhmut yesterday, our heroes gave me the flag, the battle flag, the flag of those who defend Ukraine, Europe and the world at the cost of their lives."

He said soldiers gave him the flag to bring to U.S. lawmakers, "whose decisions can save millions of people."

"So let this decision be taken, let this flag stay with you, ladies and gentlemen. This flag is a symbol of our victory in this war. We stand, we fight and we will win because we are united, Ukraine, America and the entire free world," he said, handing the flag to Pelosi.

She then gifted Zelenskyy a folded and framed U.S. flag that had flown over the Capitol on Wednesday in honor of his visit. He held it aloft, to more applause, and then exited the chamber shortly afterward.

Zelenskyy said his country will persevere through the winter and celebrate Christmas. Alluding to Russian strikes on his country's infrastructure such as its energy resources, he said, "Even if there is no electricity, the light of our faith in ourselves will not be put out."

"If Russian missiles attack us, we'll do our best to protect ourselves. If they attack us with Iranian drones and our people will have to go to bomb shelters on Christmas Eve, Ukrainians will still sit down at the holiday table and cheer up each other, and we don't have to know everyone's wish as we know that all of us, millions of Ukrainians, wish the same: Victory," he said. "Only victory."

He thanked President Biden, "both parties" of Congress and the American people for supporting Ukraine over the last 10 months.

While continuing to ask for help with weapons and financial assistance, Zelenskyy reminded lawmakers that he has never asked for U.S. troops on the ground, which American leaders have long resisted.

"I believe in us and our alliance. Ukraine never asked the American soldiers to fight on our land instead of us. I assure you that Ukrainian soldiers can perfectly operate American tanks and planes themselves," he said to some laughs and applause.

"Your money is not charity. It's an investment in the global security and democracy that we handle in the most responsible way," he said, also to applause and cheers.

The speech comes as lawmakers consider billions in additional aid to Ukraine as part of a larger government spending package, which is seeing resistance from some House Republicans and calls on the right for more oversight on funding to the war-torn country.