The announcement came days after Chinese President Xi Jinping told the UN that the world's largest greenhouse gas polluter would peak emissions in 2030 and attempt to go carbon neutral by 2060, a move hailed by environmentalists.
"We have champions and solutions all around us, in every city, corporation and country," UN Secretary-General Antonio Guterres said.
"But the climate emergency is fully upon us, and we have no time to waste. The answer to our existential crisis is swift, decisive, scaled up action and solidarity among nations."
The world remains off-track to limit global temperature rise to 1.5 degrees Celsius by the end of the century, which scientists say is crucial to prevent runaway warming that would leave vast swathes of the planet inhospitable to life.
"In light of this urgency, the Secretary-General Antonio Guterres and the UK Prime Minister Boris Johnson will co-host a landmark global event convening global leaders... to rally much greater climate action and ambition," the statement said.
The two were to address the issue at a climate roundtable meeting hosted by Guterres on Thursday.
National governments will be invited to present more ambitious and high-quality climate plans at the summit, which would involve government leaders, as well as the private sector and civil society.
According to the UN, the December 12 summit is intended to increase momentum ahead of the United Nations Climate Change Conference (COP 26) to be held in Glasgow in November 2021.
Recent data shows greenhouse gas concentrations reaching record levels, worsening extreme events including unprecedented wildfires hurricanes droughts and floods.
