Tusk's Office shared the letter on the X social media platform on Wednesday night.
In the letter, dated December 13, Biden congratulated Tusk "on your election as Prime Minister" and extended "best wishes for your every success in your service to all the people of Poland."
He described Poland as one of America's closest partners and "most steadfast allies."
The US president commended Poland for helping strengthen NATO's eastern flank, and for its "resolve and generosity" in supporting Ukraine and its people amid the Russian invasion.
Biden said he looked forward to "our continued close cooperation on Ukraine as it defends its sovereignty and territorial integrity against Russia's brutal onslaught."
The US president vowed America would "continue to stand with Poland and push back against the encroachment of authoritarianism in Europe."
Biden said he was "confident that together we will advance our shared prosperity, security and democratic values."
(pm)
Source: Chancellery of the Prime Minister of Poland, interia.pl