REUTERS/Greg Baker/Pool U.S. President Barack Obama (L) and Chinese President Xi Jinping toast at a lunch banquet in the Great Hall of the People in Beijing.
The most stunning agreement tackled climate change, where the two countries agreed to landmark new targets to curb carbon emissions.
"This is a major milestone in the US-China relationship, and it shows what's possible when we work together on an urgent global challenge," President Barack Obama said while announcing the agreement in a press conference with Chinese President Xi Jinping.
"In addition, by making this announcement today, together, we hope to encourage all major economies to be ambitious - all countries, developing and developed - to work across some of the old divides so we can conclude a strong global climate agreement next year."
Here are some of the broad details of the agreement, which came after months of behind-the-scenes negotiations between the countries on a range of issues:
The US pledges to further cut net greenhouse-gas emissions by 26% to 28% from 2005 levels by 2025.
China pledges to peak greenhouse-gas emissions by 2030, with a target of peaking even earlier. China also pledges to increase its non-fossil fuel share of energy to "around" 20% by 2030.
To meet the new goal, the US will have to double the race of carbon-emission reduction from 2020-2025. Currently, the average annual reduction pace is 1.2% per year - that number will go up to 2.3% to 2.8% per year.
The agreement is the first time China has ever agreed to peak its emissions, previously putting the burden on more industrialized countries. But together, the US and China account for about one third of the world's greenhouse gas emissions.
China's new goal of increasing the non-fossil fuel share of its energy to 20% will require it to deploy 800-1,000 gigawatts of nuclear, wind, solar, and other zero-emission generation capacity by 2030.
REUTERS/Larry Downing Mitch McConnell called the deal "unrealistic."
In the US, Democrats applauded the agreement, but the new Republican majority in Congress said it would work to broadly counter Obama on his environmental agenda.
"Our economy can't take the president's ideological war on coal that will increase the squeeze on middle-class families and struggling miners," incoming Senate Majority Leader Mitch McConnell said in a statement.
"This unrealistic plan, that the president would dump on his successor, would ensure higher utility rates and far fewer jobs."