The forecast by Mateusz Morawiecki comes amid rising anti-immigrant sentiment in the UK following the 23 June EU Referendum.
This includes the death last week of a Polish man in the UK. Six teenage boys have since been arrested over his death in Essex. One line of inquiry is the possibility of it being a hate crime.
Prosecutors in Poland have launched their own investigation into the death of Arkadiusz Jóźwik, saying that - under its laws - the accused are liable to face trial there.
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Under Polish law, foreigners who commit crimes against Polish citizens are subject to trial before a Polish court, said Warsaw's regional prosecutor, Jakub Romelczyk.
He said, "Our investigation is independent from legal action taken in the state where the crime was committed."
Speaking separately, Morawiecki estimates almost a quarter of all Polish citizens living in the UK will return to their home country when Britain leaves the EU.
He cited a growing economy and low levels of unemployment in Poland as draws for reverse migration.
Polish nationals have overtaken Indians to become Britain's biggest immigrant group after 11 years of large scale migration since Poland joined the EU.
There were an estimated 831,000 Polish-born residents in 2015 - a jump of almost three quarters of a million compared to the number in 2004 - the year the country joined the EU.
It means Poland overtook India, which had 795,000 people last year, as the most common non-UK nation of birth.
The number of EU citizens living in the UK topped three million for the first time last year.
In a separate development, the Polish foreign ministry said it had raised the issue of attacks on Poles living in the UK with British foreign secretary, Boris Johnson.
This follows a similar discussion between Johnson and his Polish counterpart, Witold Waszczykowski, at a meeting of EU foreign ministers in Potsdam last week.
Waszczykowski said that, at that earlier meeting, Johnson "promised to address the issue" and gave assurances that the "UK government does not accept the hate action against migrants and it will do everything to protect Poles and other foreigners against aggression."
The Polish foreign minister has also suggested that an educational campaign should be introduced in Britain "so as to make people aware that Brexit will not mean throwing immigrants out from the UK."
Meanwhile, Japan's government has warned that Brexit could result in the country's firms moving their European head offices out of Britain.
The strongly worded report from Japan's foreign ministry says the firms might want to move "if EU laws cease to be applicable in the UK."
The letter emerged during the G20 summit in China at the weekend, attended by both Japan and the UK.
It calls on Theresa May's government to deal with the companies' concerns in a "responsible manner."
Japanese firms employ an estimated 140,000 workers in the UK, with Nomura bank, manufacturing giant Hitachi and carmakers Honda, Nissan and Toyota all having major bases in the country.
The letter warns: "Japanese businesses with their European headquarters in the UK may decide to transfer their head-office function to continental Europe if EU laws cease to be applicable in the UK after its withdrawal."