Zelenskyy opened his speech to a joint meeting of Congress with a direct address to the American people, appealing to shared values of freedom, justice and family in what read out like a letter.

"Dear Americans, in all states, cities and communities -- all those who value freedom and justice, who cherish, as strongly as we Ukrainians, in our cities in each and every family, I hope my words of respect and gratitude resonate in each American heart," he began.

"Dear members of Congress, representatives of both parties who also visited Kyiv, esteemed congressmen and senators from both parties who will visit Ukraine, I am sure in the future," he continued. "Dear journalists, it's a great honor for me to be at the U.S. Congress and speak to you and all Americans."

"Against all odds and doom and gloom scenarios, Ukraine didn't fall," he said. "Ukraine is alive and kicking."

After President Biden's Cabinet walked in, Zelenskyy entered the House chamber to a standing ovation and roaring applause, accompanied by members appointed by House Speaker Nancy Pelosi to escort him.

Zelenskyy, who just one day earlier was visiting soldiers on the front lines of fighting, continued to don his signature army green sweatshirt, green pants and combat boots as he walked up to give his first in-person address outside of Ukraine since Russia's invasion began -- and became the first wartime foreign leader to address Congress since the U.K.'s Winston Churchill during World War II

Zelenskyy stopped to shake lawmakers' hands along the aisle and grabbed hands with Vice President Kamala Harris and Pelosi.

Ahead of Zelenskyy's entrance, Senate Majority Leader Chuck Schumer relayed this message from their closed-door meeting: "He made it clear that without this aid package, the Ukrainians will be in real trouble and could even lose the war."

Presiding over the House chamber, Speaker Nancy Pelosi wore a blue suit with a broach -- the "Order of Olga the Duchess of 3rd Degree," a Ukrainian civil decoration given to her by Zelenskyy when she was in Kyiv, her office said.

Pelosi visited Ukraine in May, marking the first official congressional delegation since Russia invaded.

Here is some early color ahead of Zelenskyy's scheduled 7:30 p.m. remarks to a joint meeting of Congress:

The mood is good inside with members mingling. Early attendees included incoming House Minority Leader Hakeem Jeffries, D-N.Y., and Republican Reps. Matt Gaetz of Florida and Lauren Boebert of Colorado.

Gaetz has been one of the most vocal critics in Congress of future Ukraine funding, vowing a few weeks ago not to support additional money.

Some members are wearing yellow scarves and yellow suit jackets -- an apparent reference to solidarity with Ukraine.

Shortly ahead of Zelenskyy's address, House Speaker Nancy Pelosi welcomed senators to the House chamber for the joint meeting, including Vice President Kamala Harris, president of the Senate.

Wyoming Republican Rep. Liz Cheney was seated on the Democrats' side of the House chamber next to lawmakers she served with on the Jan. 6 committee.

-ABC News' Will Steakin