The prime minister pledged the cash with the aim of helping children spend 12 years in school at a speech at the ongoing biennial Commonwealth heads of government meeting (CHOGM) in London.
In front of an audience including Microsoft founder, philanthropist and anti-malaria campaigner Bill Gates, Ms. May also urged leaders from the bloc’s 53 nations to work to halve the number of those afflicted by 2023.
Ms. May said the 12-year figure agreed by experts as the length of time children should be schooled to reach their full potential should be the “goal for all our members”.
She said: "Across the Commonwealth, tens of millions of young people – usually but not always girls – are denied the education that would allow them to get on in life.
"All our members have pledged to “ensure inclusive and equitable quality education and promote lifelong learning opportunities for all”.
"But all too often young people receive only the most basic education before being forced out of school through discrimination, poverty, or simply the expectations of society."
Downing Street said the money would “see nearly one million more girls in developing Commonwealth countries being able to go to school”.
On Monday, Ms May highlighted the importance of getting women into work and cited estimates that global GDP could be increased by up to £19.5trn if women played the same role as men in the labor market.
Ms May also set her sights on tackling malaria, one of the world’s deadliest diseases, saying: “The UK remains committed to its five-year pledge, made in 2016, to spend half a billion pounds a year tackling malaria.
“This year, that figure includes £100m that will be match-funded by partners in the private sector.
“I know other Commonwealth nations are also among the biggest funders of this global effort.
“Malaria devastates lives worldwide but it has a particular impact on the Commonwealth. And we, as a Commonwealth, have a particular duty to tackle it.”