Saakashvili said at a news conference in Warsaw that he wanted to return to Ukraine, where he has been an opposition leader, and would shortly make a decision on his next step.
He said that he had been expelled because Ukrainian President Petro Poroshenko wanted to get rid of his most dangerous opponent.
Saakashvili added that he would continue to fight what he described as corrupt oligarchies in Ukraine and Georgia.
Saakashvili was deported to Poland on Monday, Ukrainian border guards said after he was detained in Kiev.
Saakashvili moved to Ukraine in 2014, when he was an ally of Poroshenko. But he was stripped of his Ukrainian citizenship last year amid a standoff with the authorities in Kiev, whom Saakashvili accuses of corruption.
According to Ukrainian officials, Saakashvili entered the country illegally from Poland in September.