"Since February 24, around 3.57 million people have crossed into Poland from Ukraine," it said in a tweet.
On Monday, 18,500 refugees from Ukraine arrived in the country, compared with 20,000 a day earlier, according to the Polish Border Guard.
While most of those crossing the border are Ukrainian nationals, there are also citizens of many other countries among the refugees, public broadcaster Polish Radio’s IAR news agency has reported, citing the foreign ministry in Warsaw.
Poland in March enacted a measure to offer wide-ranging support to Ukrainians escaping the Russian invasion of their country, which began on February 24.
The measure grants them residence rights and ensures access to education, healthcare and social benefits.
More than 90 percent of Poles are in favour of accepting refugees from war-torn Ukraine, according to a survey.