Paterson, New York's first black governor, said the election of the nation's first black president was "a realization of the long-held dreams of generations of Americans who have fought and continue to fight against the ugliness of inequality in all its forms."
"Now we must set aside our differences and join together to support the new administration," the governor said in a statement. "There is no doubt that our nation, and our state, is facing enormous challenges, the worst we have seen since the Great Depression."
Bloomberg, the billionaire mayor, had spent months testing the waters to see if he had any chance at winning the White House as an independent candidate.
As Obama and Republican John McCain began to emerge as front-runners earlier this year, Bloomberg ultimately concluded he could not win because they both appealed to independent voters that he would have sought to attract.
Bloomberg hinted for months that he might make an endorsement, but ultimately said he did not want to hurt any of his relationships in Washington.
The mayor said Wednesday that the country must now pull together, "both major parties and all those in the middle."
Paterson said, "We have a lot of work to do at every level of government, but we also share a new resolve to accomplish great things together in the months and years to come."