President Mikhail Saakashvili has arrived in the province of Ajaria to scenes of jubilation a few hours after forcing its rebel leader to resign.
Fears of violence proved unfounded
Aslan Abashidze ended more than a decade in power by flying with his family to Moscow after talks with a Russian envoy on Wednesday night.
"You are heroes," Mr Saakashvili told well-wishers from a window in Mr Abashidze's former residence in Batumi.
Ajaria's return to Georgian control comes just months into his presidency.
People in the crowd chanted his nickname - Misha - and waved the country's new red and white flag, as what had been protest rally became a celebration in the capital of the Black Sea province.
The collapse of Mr Abashidze's rule came after a month-long confrontation during which his heavily armed supporters at one point blew up bridges leading into Ajaria from Georgia proper.
Ahead of his talks with Russian Security Council Secretary Igor Ivanov, Mr Abishidze had been saying he had "no intention" of quitting Ajaria.
However, pressure came to a head on Wednesday when the president declared direct presidential rule and offered Mr Abishidze safe passage abroad.
Announcing the rebel leader's resignation on TV on Wednesday night, President Saakashvili said he wished to mark "the beginning of Georgia's unification".
"Georgia will be united," he declared, in an apparent reference to two of the tiny Caucasus republic's other regions, South Ossetia and Abkhazia, which have been out of Tbilisi's control for years.
Population: 400,000; overall population of Georgia: 5 million
Depends on income from transited goods, its port shipping about 200,000 barrels of oil a day
Has run its own affairs for years, withholding tax payments from central government in Tbilisi
Ajarians are ethnic Georgians but mostly Muslim, unlike the majority in the Orthodox Christian state
Presidential staff, however, have stressed that the problems there are quite different, involving ethnic conflicts.
Mr Saakashvili last year led a peaceful uprising to overthrow his predecessor, Eduard Shevardnadze. He took office in January after a landslide election win.
Mr Abashidze, a Soviet-era politician, had maintained strong links with Russia during his rule and strongly opposed the Western-leaning Mr Saakashvili.
The crisis aroused the concern of Russia, Europe and the US, all of whom consider the Black Sea state to be of key strategic importance.
The US is backing the construction of a multi-billion dollar pipeline to transport Caspian Sea oil through the volatile region to the international market.
Russia, a giant among the world's oil exporters, retains a military base in Ajaria, where there is a substantial ethnic Russian community.