She made the statement on Twitter after a meeting with Polish First Lady Agata Kornhauser-Duda at the White House on Wednesday.
Jill Biden tweeted: "I was so proud when the people of Poland welcomed Joe to Warsaw last week, and today, I had the chance to return the kindness to First Lady Kornhauser-Duda at the White House."
Jill Biden added: "Together, we continue to be united in our support for Ukrainian refugee families."
The Polish and US first ladies met at the White House on Wednesday to discuss help for Ukrainian children traumatised by war, according to the Polish ambassador to the United States, Marek Magierowski.
US President Joe Biden said in a Twitter post at the end of last week that America's relationship with Poland was "critical" for the two nations, especially in the face of Russia's war in Ukraine.
Joe Biden visited Poland last week for bilateral talks with Polish President Andrzej Duda. He also delivered a major address outside Warsaw’s Royal Castle and met with leaders from nine NATO eastern-flank countries in the Polish capital.
The US leader told the nine eastern-flank NATO allies last Wednesday that Article 5 of the alliance's collective defence treaty "is a sacred commitment” and that America "will defend literally every inch of NATO."
In a major speech in Warsaw on February 21, Joe Biden vowed that America and its allies "will not tire" of supporting Ukraine and that "Ukraine will never be a victory for Russia."
Source: PAP, prezydent.pl