The eastern European country is “so dependant on the EU” it “could not cope” with a Brexit-style split with Brussels, Sebastian Becker said.
Mr Becker, the editor of global economic publication OWC, said the Polish economy would collapse in the event of “Polexit” if the country was forced to repay the £81.6bn (€92.6bn) it has received since joining the bloc in 2004.
The warning comes just days after Poland’s new Prime Minister clashed with the EU over its plans for further intergration.
And an ongoing row between Warsaw and Brussels over refugees threatens to worsen relations at a time when support for Polish independence continues to grow.
Writing on the OWC website, Mr Becker said the Polish economy is so dependant on exports to EU member states, particularly Germany, leaving the union would result in a huge black hole in its finances.
He said: “As strong as the political demands of the right-wing politicians may be at the moment, they can not be economically justified.
“Economically, a withdrawal of Poland would be hard to afford. One could even speak of an economic lunacy.”
He added the £162bn (€184bn) of Polish exports which go to EU member states “would almost be irreplaceable”.
In addition to the massive loss in GDP, Poland would be bankrupted if it was forced to pay a divorce bill for leaving, Mr Becker said.
The country has received far more from Brussels than it has paid in during its 13 years an EU member state.
Mr Becker said: “Since joining in April 2004, around €138bn have gone to Warsaw, while Poland has contributed almost €46bn.
“In total Poland has received a plus of €92.6bn – more than a fifth of its annual gross domestic product.
“If Poland had to repay this huge sum after leaving the country, that would mean the collapse of the entire economy.”
Last week, Poland’s new PM Mateusz Morawiecki hit out at the EU’s plans for deeper integration between eurozone countries.
The plans, which are being pushed by France and Germany, would see greater financial cooperation but critics have warned it will create a “multi-speed” Europe, with some countries integrating faster than others.
In his first policy speech since being sworn in, Mr Morawiecki said: ”We don’t want further divisions… we oppose splitting of Europe between those are who better and those who are inferior.”
And earlier this month, the EU moved to punish Poland over its refusal to accept refugees by attempting to suspend its voting powers in the European Council.
The eastern European country has not taken in any refugees or asylum seekers since the refugee crisis began in 2015.
But Renata Mienkowska, a political scientist at the University of Warsaw, warned the EU’s actions mould only serve to push Poland further away from the bloc.
She said: “It hurts me to say that, but an EU exit from Poland is absolutely possible.”
Additional reporting by Monika Pallenberg