Until Thursday night, the 48-year-old opposition MP had not been seen for almost two weeks.
He reportedly had not used his phones or bank cards since 6 December and failed to attend a court hearing three days later that ruled he be remanded in custody before trial.
On Thursday, a European Arrest Warrant was issued by a Warsaw court acting on prosecutors’ information he had fled to an EU country.
There had been speculation that Mr Romanowski was in hiding in Hungary.
On Thursday, Hungarian Prime Minister Viktor Orban said the current Polish government was treating Hungary as an enemy and he would offer refuge to anyone facing political persecution in Poland.
Mr Orban and Poland’s Law and Justice party share ideological goals even though they fell out over Russia’s invasion and war against Ukraine.
They broadly agree that what they consider a liberal EU-elite is driving Europe away from its Christian traditions and eroding member states’ sovereignty.
Mr Romanowski is reportedly a member of conservative Catholic group Opus Dei, who issued a denial earlier this week that the MP was being hidden by them.
In October 2022, he told a Polish Catholic radio station that LGBT+ was “institutionalised deviancy”.
A year later he advocated the death penalty, even for minors, after a 16-year-old boy was beaten to death by teenagers.