Georgia is a "beacon of liberty for the region and the world", US President George W Bush has told a cheering crowd in the former Soviet republic.
Mr Bush thanked Mr Saakashvili for sending troops to Iraq
Georgia's peaceful Rose Revolution set an example for others, including Ukraine, Iraq and Lebanon, he said.
Mr Bush spoke in Tbilisi's Freedom Square - the place where Georgians celebrated ousting the old regime.
His trip to Georgia, the first by a US leader, gave new support to Georgian President Mikhail Saakashvili.
"You gathered here armed with nothing but roses and the power of your convictions and you claimed your liberty," Mr Bush told thousands gathered in the square.
Nearby buildings had been painted for his visit, and huge banners read: "Celebrating freedom and democracy."
Mr Bush called on other nations to respect Georgia's sovereignty and territorial integrity, and he reaffirmed Washington's support for Georgia to eventually join Nato.
Earlier, at a joint news conference, Mr Saakashvili said the US president was a "decisive and visionary leader", and he thanked him for his support following the Rose Revolution that ousted President Eduard Shevardnadze in 2003.
"No country stood closer to Georgia than the US," the US-educated leader said, pledging to "widen and deepen democratic reforms".
Mr Bush offered to help Georgia resolve its disputes with the breakaway regions of South Ossetia and Abkhazia - giving his backing to Mr Saakashvili's plan to give them some autonomy but not full independence.
"The United States cannot impose a solution nor would you want us to," Mr Bush said. "But what we can do is to work with international bodies. We can work with the UN for example."
Rift with Moscow
Mr Bush said he had spoken to Russian President Vladimir Putin about Georgia's demand for the closure of two Russian bases on its territory, expressing confidence that the two sides could agree a timetable.
Mr Saakashvili boycotted Monday's World War II commemorations in Moscow in protest at Russia's continued presence, as well as the Kremlin's support for Abkhazia and South Ossetia.
Moscow appears uneasy at the US friendship with Georgia
Georgia is one of the countries that best illustrates Mr Bush's central foreign policy theme - the need to spread freedom and democracy, says the BBC's James Coomarasamy in Tbilisi.
But he says Mr Bush's visit has concerned the Kremlin, which fears the US agenda could undermine Moscow's traditional influence in the region.
Mr Bush said he hoped Russia would one day "recognise the benefits" of having democracies on its borders.
On Monday night, the US and Georgian presidents and their wives attended an open air concert of Georgian folk music and dance in Tbilisi's historic town centre. At one point Mr Bush even decided to join in.
"I learned first hand what it means to be fed by a Georgian," Mr Bush said at the news conference. "I'm really full. And the food was great."