The Queen is making a personal donation towards helping the millions of people who face starvation in East Africa.
The announcement comes after Boris Johnson paid a surprise visit to Somalia and as Sir Mo Farah backed a charity appeal for the cause.
A Buckingham Palace spokesman said: "I can confirm that Her Majesty is making a personal donation to the Disasters Emergency Committee's East Africa Crisis Appeal."
Britain has pledged to match public donations up to £5 million for the Disasters Emergency Committee's (DEC) East Africa Crisis Appeal, which seeks to help more than 16 million people "on the brink of starvation and in urgent need of food, water and medical treatment".
Videos will air on the BBC, ITV, Channel 4, Channel 5 and Sky in an appeal to get the British public to donate money to help those trapped in the crisis, caused by droughts and conflict.
Sir Mo, who spent his early childhood in some of the worst affected areas of Somalia, said he was "completely devastated", urging people to "act now".
Money raised by the DEC appeal will help those affected in Somalia, Kenya, Ethiopia and South Sudan, with the Government pledging to match public donations pound for pound, up to £5 million.
Between the four countries, around 800,000 children aged between six months and five years need life-saving treatment for severe acute malnutrition, said the DEC.
While in Somalia, the Foreign Secretary met President Mohamed Abdullahi Mohamed, who was elected last month.
He also saw demonstrations of the training the British Military is providing to Somali National Army (SNA) and African Union Mission to Somalia (AMISOM) forces.
The training will help Somali forces combat terrorism and take responsibility for the security of their country.
Speaking after the trip, Mr Johnson said he was "delighted" to meet the country's president, and prime minister Hassan Ali Khayre.
He added: "I heard about their plans and priorities and we discussed how we can work together to improve security and deliver the economic development that Somalia needs to improve the lives of all its people.
"I was particularly impressed by the demonstrations of the practical help that the UK is delivering on the ground, from our military providing essential training for Somali armed forces to the live-saving humanitarian support from UK Aid. All of this is vital if Somalia is going to move forward to achieve long-term stability and prosperity.
Mr Johnson will next be visiting Uganda, Ethiopia and Kenya.
He will discuss regional security, prosperity and the London Somalia Conference on May 11 2017 and the Commonwealth Summit in April 2018.
Mr Johnson made a direct appeal to Britons to donate money, telling BBC Radio 4's PM: "It would be very well-spent in my view.
"You have probably 6.2 million people who are at risk of famine, kids dying of cholera in this country, and the cash that we are giving as the UK is, I believe, having an immediate impact."