Chancellor Gordon Brown has said the UK will give $15bn (£8.5bn) in overseas aid for education in Africa and Asia.
The chancellor is making his second visit to Africa in 18 months
The 10-year funding plan is part of the pledge by the world's richest nations to help every African child have access to a primary school by 2015.
Speaking during a visit to a school in Mozambique, Mr Brown said: "In 2005, Make Poverty History forced governments to make promises on aid.
"Now, in 2006 it is time for us to keep our promises."
International Development Secretary Hilary Benn meanwhile said: "Education is a basic human right, and to get every child into school we need more investment.
"Working with developing countries, through increased commitment from the UK, will help train more teachers, build more classrooms and give more children the best start in life."
Conservative international development spokesman Andrew Mitchell warned "noble rhetoric" often failed to become "effective action on the ground".
"It appals us all that over 100 million children around the world are missing out on an education," he added.
"This is a waste of talent and potential. If British taxpayers' money is spent well, it has the potential to make a real difference, but only if we monitor continually the outputs, results and effectiveness."
Meanwhile Live 8 organiser Bob Geldof said: "Education for all in Africa is essential for the eventual eradication of poverty and was one of the historic promises made by the G8 at Gleneagles.
"In the next few weeks and months, starting at the World Bank Spring Meetings in Washington, the leaders and finance ministers of the G8 must deliver as Gordon Brown has done so impressively today."
Mr Brown and the former South African president Nelson Mandela are challenging world leaders to honour the pledges made last year.
In 2005 the international community agreed to provide an extra $50bn a year in aid - the money earmarked for education spending is part of the UK's contribution to that total.
Mr Brown and Mr Mandela also urged African countries to increase links with UK schools.