"Since February 24, a total of 5,274,000 people have crossed into Poland from Ukraine," it said in a tweet.
On Thursday, around 25,000 refugees from Ukraine arrived in the country, compared with 24,300 a day earlier, according to the Polish Border Guard.
Meanwhile, more than 3.38 million people have left Poland for Ukraine since February 24, the agency also reported.
On Thursday, around 25,000 people crossed from Poland into Ukraine, the Polish Border Guard said.
A deputy interior minister said in mid-June that Poland was home to some 1.5 million Ukrainians after many refugees from Russia's invasion of Ukraine decided to return to their country.
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.
Eighty-four percent of Poles are in favour of accepting refugees from war-torn Ukraine, according to a new survey.