Poland's Foreign Minister Radosław Sikorski confirmed Mariusz Majewski's release and safe arrival in Europe.
"This morning we were finally able to talk," Sikorski said, sharing an excerpt from his conversation with Majewski, who officials said was staying at the Polish consulate in Brussels.
Majewski had been wrongly convicted on charges of espionage, sabotage and destroying military installations, according to reports. He was freed following diplomatic efforts by Polish authorities.
Majewski, an avid traveler and member of a travel club, was sentenced by a military tribunal on May 23. In March, he faced a military court in a show trial attended by 200 people.
His presence near sensitive sites was accidental and resulted from his lack of familiarity with local customs, according to Polish officials.