Obama's Air Force One jet landed at Belfast International Airport outside the capital shortly after 8:35am (0735 GMT). He is due to give a speech in the city centre before meeting President Putin for talks.
Obama disembarked with his wife Michelle and their two daughters, transferring to a helicopter to fly to the smaller Belfast City Airport near the city centre.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Obama was heading to the Waterfront Hall conference centre to speak to an invited audience of 2,000 mostly young people, touching on Northern Ireland's peace process.
He was to be greeted by Northern Ireland's First Minister Peter Robinson and his deputy Martin McGuinness on his first visit to the province.
Obama was then to meet Putin for potentially difficult talks, with both leaders now offering open military backing to rival sides in Syria's civil war.
Obama will confront the Russian premier at the G8 after his administration signalled it would begin arming vetted rebels battling Syria's government, Russia's top Arab ally.
That decision last week complicated the already delicate politics of the Obama-Putin meeting and prompted Russia to acidly decry US claims that Syria crossed a 'red line' by using chemical weapons as unconvincing.
Washington, trying to preserve the troubled notion of a Geneva peace summit co-organised with Moscow, wants a change of strategy from Putin, who has backed President Bashar al-Assad even as Obama has repeatedly demanded he leave power.
But no one expects the Russian leader to yield, especially in the wake of battlefield gains against the rebels by Assad's forces bolstered by Hezbollah militia fighters and Iran.
Putin may also be taking some Machiavellian comfort from the public agonising consuming Western governments over what to do about Syria, which has been particularly acute inside the Obama administration.
"We still continue to discuss with the Russians whether there is a way to bring together elements of the regime and the opposition to achieve a political settlement," said Ben Rhodes, a deputy US national security advisor.
"There are no illusions that that's going to be easy."
US officials will try to convince Putin that a descent into deeper chaos and instability in Syria is not in Moscow's national interests.
Top US officials, keen to avoid in Syria the messy splintering of state institutions that led to chaos in Iraq, are stressing the idea that if Assad leaves, elements of the regime, presumably sympathetic to Russia, might stay.
But the argument's potency has weakened given indications that Assad's position is more stable than it has been for months.
Obama may press Putin on whether Russia plans to complete the delivery of S-300 anti-aircraft missiles to the Damascus regime -- which could complicate any future US or Western air operations over the country.
Beyond the talks on Syria, Obama will likely probe whether Putin is ready to talk about weapons cuts as he seeks to cement his nuclear arms reduction legacy after agreeing on a new START treaty with Moscow in his first term.
