The press release cites security concerns as the reason for the decision.
State Department personnel are expected to regularly return to Ukraine to continue diplomatic work and emergency consular support.
The release acknowledges that the removal of US personnel could be viewed negatively by Ukrainian officials, reading, "The fact that we are taking prudent precautions for the sake of the safety of US government personnel and US Citizens, as we do regularly worldwide, in no way undermines our support for, or our commitment to, Ukraine. Our commitment to Ukraine transcends any one location".
The release offered no details for the security concerns cited as a catalyst for US Department of State personnel being moved to Poland for the night.
The Biden administration has been reported to be mulling ordering the relocation of all US diplomats still remaining in Ukraine to Poland. The report also suggested that American personnel could return to Ukraine on Tuesday if there is no Russian invasion.
US Embassy staff had previously relocated from Ukraine's capital city of Kiev to Lvov.
Earlier on Monday, Russian President Vladimir Putin formally acknowledged the Donetsk People's Republic and the Lugansk People's Republic. Russia is the first United Nations member nation to acknowledge the two breakaway states, but the US and Ukraine have consistently rebuffed their sovereignty.
The two regions are predominantly Russian-speaking and ethnic Russians make up a sizable minority. The Donetsk People's Republic and the Lugansk People's Republic are in eastern Ukraine.
Later on Monday, the Russian military entered the region to help maintain peace.
Over the past weeks, the United States and its NATO allies have accused Russia of massing troops along Ukraine's border ahead of an invasion.
Russia has consistently denied the accusations.