Obama, who also won Ohio in 2008, claims the swing state's 18 electoral votes.
Both sides poured major time and resources into the battleground state that has been among the nation's most contested in recent presidential elections. It was considered pivotal for both.
No Republican has won the White House without Ohio. The last president elected despite losing Ohio was Democrat John F. Kennedy in 1960.
Ohio has been site of much of the advertising spending by the campaigns and outside supporters. It also was among the most-visited states by the campaigns.
In addition to Ohio, Obama captured battleground states Iowa and Colorado on his way to the 270 electoral votes he needed.
Obama will again be dealing with a divided Congress. Democrats maintained control of the Senate and Republicans likely will again control the House. Among the most pressing matters is the so-called fiscal cliff of tax hikes and spending cuts scheduled to hit in January. Economists have warned that if they aren't averted, the nation could face another recession.