The umbrella group of charities says an estimated 2.6 million people have been caught up in the devastation left by the cyclone that struck last week. More than 1,000 people have died.
Houses, roads and bridges have been ripped apart and agricultural land is completely submerged. More than 480 people are confirmed dead and 400,000 have lost their homes.
The full scale of the disaster is still unfolding as search and rescue operations continue and more heavy rain is predicted.
The UN fears that this may become one of the worst weather-related disasters on record in the southern hemisphere.
DEC members are working closely with national partners to support the relief effort, delivering emergency shelter kits, food such as pulses and maize flour, water purification tablets and urgent health assistance.
The BBC, ITV, Channel 4, Channel 5 and Sky will be broadcasting appeals on Thursday evening in support of DEC fundraising.
Every pound donated by the UK public will be matched by the UK government through its Aid Match scheme up to the value of £2 million.
This new support will double the impact of the public’s own donations and will ensure that charities working on the ground can reach the men, women and children who have been left homeless and are in urgent need of food, water and temporary shelter.
Britain has pledged a further £12 million in aid to help survivors, which brings the Government's total donation in the aftermath of the cyclone to £18 million.
To donate £5, text SUPPORT to 70000. Texts cost £5 and the whole £5 goes to the DEC CYCLONE IDAI APPEAL. You must be 16 or over and please ask the bill payer's permission. For full terms and conditions and more information go to .
To make a postal donation, make cheques payable to ‘DEC Cyclone Idai Appeal’ and mail to ‘PO Box 999, London, EC3A 3AA’.
Donations can be made at any high street bank and at Post Office counters.
Just £30 can provide blankets to keep two families warm, while £50 could provide a family with food for one month and £100 could help build toilet and washing facilities for families who lost their homes.
The DEC brings together 14 major UK aid agencies: Action Against Hunger, ActionAid UK, Age International, British Red Cross, CAFOD, CARE International UK, Christian Aid, Concern Worldwide UK, Islamic Relief Worldwide, Oxfam GB, Plan International UK, Save the Children UK, Tearfund and World Vision UK.