The DEC, made up of 15 UK charities, is urging everyone to donate whatever they can spare to help relief efforts.
DEC chief executive Saleh Saeed said that their priority is to protect lives as waters continue to rise.
“Our priority right now is to help save and protect lives as waters continue to rise,” he said.
“The scale of these floods has caused a shocking level of destruction – crops have been swept away and livestock killed across huge swathes of the country, which means hunger will follow.”
Mr Saeed acknowledged that the appeal comes at a difficult time for many Britons, as they struggle with the cost-of-living crisis.
“DEC charities are doing all they can but donations from the British public will make a huge difference in enabling them to reach more people,” he said.
“We’re urging everyone to give whatever they can at what we appreciate is a difficult time for us all.”
Pakistan has seen exceptionally heavy monsoon rains which have triggered flash floods, affecting 33 million people and damaging around one million homes.
The death toll is reported to be at least 1,162 people, with six million more in urgent need of humanitarian assistance.
On Tuesday, the United Nations launched an appeal for £138 million in emergency funding for Pakistan.