WARNING: This article contains distressing images.
More than seven million people in the war-torn country do not know where their next meal will come from and children are dying from malnutrition, the charity said.
Actor Tom Hardy and television presenter Clare Balding announced the launch of the appeal today.
The Disasters Emergency Committee (DEC), which represents 13 UK aid charities, said the country was at "breaking point".
The British Red Cross, Oxfam, Save The Children and Christian Aid are among the charities supporting the Yemen Crisis Appeal.
The DEC said member charities were already reaching "millions of people" with aid, but said: "Much more needs to be done to help those in dire need."
Oxfam previously warned Yemen will run out of food within months and its people are "at risk of catastrophic hunger".
After 20 months of conflict, malnutrition in Yemen is on the increase, with more than 14 million people - half the country’s population - categorised as ‘food insecure’ according to the United Nations.