Earlier on Sunday, Saakashvili had boarded a train in Poland heading for Ukraine, before the train was stopped by guards before the Ukrainian border.
According to France 24, he quit as governor of Odessa in November after he and current Ukrainian President Petro Poroshenko had a falling out, which led to Poroshenko revoking his citizenship in July.
"Saakashvili's return to Ukrainian politics was triumphant albeit scandalous", Mr Vadym Karasyov, director of the Kiev-based Institute of Global Strategies, said.
Before crossing the border, Saakashvili has explained stis difficulty by the fact that Kiev "panic", saying that he wanted "not to overthrow the president Porochenko" objective just to defend sti rights.
But Saakashvili was swept over the border on Sunday by a crowd of his supporters, angry that the crossing was closed.
"Instead, a crime was committed", he said of Sunday's events at the border.
But in accepting Ukrainian citizenship, he surrendered his Georgian citizenship.
Saakashvili denies the accusations branding them a political witch hunt. According to him, he left his Ukrainian passport in a bus on the border with Ukraine, but then "the police came and stole it".
No matter how hard I try, I just can't find a logical explanation that would justify the decision to stop the train from leaving and increasing security at the border.
"This passport is not the plaything of individual oligarchs, who issue it and then retract it, declare it invalid or use it to blackmail you", Saakashvili recently protested, threatening he would return to Ukraine soon, speaking to Der Spiegel. He eventually got off the train and took a bus to Medyka, where he successfully crossed the border.
The Ukrainian president added that he would respect any court ruling for Saakashvili.
Under the law, Saakashvili could face up to 5 years in prison if convicted. No need to forget that home country, Georgia, accused Saakashvili of abuse of power and misappropriation of property, now it has sent an extradition request for him to Ukraine. Saakashvili took power in Georgia after a peaceful pro-Western uprising, known as the Rose Revolution, in 2003.
The revocation of Saakashvili's citizenship was met with criticism by some Ukrainian politicians with ex-Prime Minister and Batkivshchina (Fatherland) Party leader Yulia Tymoshenko believing that this move was another step toward dictatorship in Ukraine.
"We didn't want this country when we stayed on Maidan", he told reporters.
Prosecutor-General Yury Lutsenko said late on September 10 that charges would be pursued against the people who helped organize Saakashvili's entry.