Television showed footage of President Mikheil Saakashvili and other officials holding their hands to their hearts as the national anthem played in cities across the country.
In the Georgian city of Gori, a flashpoint in the war, several hundred youths gathered in the form of a red-and-white Georgian flag in the ruins of a medieval fortress and hundreds more people created a human chain.
South Ossetia -- the breakaway region at the heart of last year's five-day conflict -- was to mark the anniversary with three days of ceremonies August 7-9, including a memorial procession, service and a moment of silence.
Russian President Dmitry Medvedev, who is lauded as a hero in South Ossetia, was expected to visit the breakaway region Saturday.
In a television interview marking the occasion, Medvedev insisted he alone had taken all the decisions on sending Russian forces into battle against Georgia last year.
"It was the hardest thing but in the end we got it right," Medvedev said.
The anniversary follows a week of rising tensions around South Ossetia and accusations from both sides of small-scale attacks and "provocations."
The United States and European Union have raised concerns about the situation and called on all sides to tread carefully.
The war began late on August 7 last year when Georgian forces launched an assault on South Ossetia following days of escalating violence.
Russia's military responded with a swift and relentless counter-attack, driving Georgian forces out of the rebel region and then pushing deep into Georgian territory.
An EU-brokered ceasefire ended the conflict five days later after several hundred people had been killed and thousands wounded. Russian forces later mostly withdrew to within South Ossetia and another rebel Georgian region, Abkhazia, and recognised both as independent states.
The speaker of Georgia's parliament, David Bakradze, said Friday that Russia had failed in its goal during the war to "eliminate the Georgian state.
"Our struggle will continue until Georgia's freedom and unity are secured," he said in televised remarks.
London-based rights group Amnesty International said Friday that some 30,000 people, mostly ethnic Georgians, remain displaced and were prevented from returning home by "an omnipresent sense of tension and insecurity."
Russia insists it moved into Georgia to defend South Ossetia from a Georgian attack and on Friday Russian prosecutors released a report claiming Tbilisi intended to "eliminate the Ossetian people."
Georgia earlier sought to boost its claim that Russia was to blame for the war by releasing a report detailing its longstanding contention that it launched its assault to defend against a "large-scale Russian invasion."
Both sides accused the other of spinning the truth through slick international propaganda campaigns.
"Russia's propaganda machine has spent tens and hundreds of millions on anti-Georgian propaganda ... to convince the world that Georgia is to blame for what happened," Saakashvili said in televised remarks.
Russia's deputy chief of staff, Anatoly Nogovitsyn, shot back: "Like last year, you can see the fingerprints of the Western PR agencies" all over Georgia's international communication effort.
Violence flared in the run-up to Friday's anniversary, with Georgia and South Ossetia accusing each other of carrying out several small-scale attacks with mortars, grenade launchers and machine guns. No one was reported injured.
The EU issued a statement calling for calm and US President Barack Obama and Vice President Joe Biden called Moscow and Tbilisi, respectively, shortly before the anniversary to urge restraint.
The war was a dramatic projection of Russian power and interests in the former Soviet Union, where Washington's efforts to boost US influence in areas long under Russian sway have deeply angered the Kremlin.
Dismissing pleas from the West, Russia has entrenched its positions in South Ossetia and Abkhazia since the war, gaining a key foothold in the strategic Caucasus region, a vital oil and gas transport corridor.