"We came together around a strong agreement the world needed," said Obama, speaking from the White House. "We met the moment."
Obama added, "This agreement represents the best chance we have to save the one planet that we've got."
The accord sets a goal of limiting average warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial temperatures -- and of striving for a limit of 1.5 degrees Celsius (2.7 degrees Fahrenheit) if possible.
Obama has long sought to make combating climate change a significant part of his domestic presidential legacy but has been stymied by Congress, which hasn't approached significant legislative action on climate change since a cap-and-trade bill failed in 2009 and 2010.
The Paris deal was described by senior administration officials Saturday as a "hybrid agreement" where parts of the agreement, such as the transparency of countries sharing their carbon emissions, would be legally binding. The actual emission standards numbers, however, are not legally binding, according to officials.
"This agreement does not require submission to the Senate because of the way it's structured," a senior administration official told reporters in a conference call.
"The pieces that are binding are already part of existing agreements," the official added.
Most Republicans oppose Obama's unilateral actions on climate change, and many have expressed doubts that humans are responsible for warming temperatures.
Sen. Jim Inhofe, the Republican chairman of the Senate Environment and Public Works Committee and a climate change skeptic, rebuked the legitimacy of the deal Saturday.
"This agreement is no more binding than any other 'agreement' from any Conference of the Parties over the last 21 years. Senate leadership has already been outspoken in its positions that the United States is not legally bound to any agreement setting emissions targets or any financial commitment to it without approval by Congress," Inhofe said in a press release.
Secretary of State John Kerry responded to Inhofe's comments from Paris, telling reporters, "I have news for Senator Inhofe: The United States of America has already reduced our emissions more than any other country in the world under President Obama's plans."
Obama added that Saturday's agreement is the first of many.
"The problem's not solved because of this accord, but make no mistake, the Paris agreement establishes the enduring framework the world needs to solve the climate crisis," he said.