Mary's Meals, named after the Virgin Mary, mostly operates in Malawi, one of the poorest and least-developed countries in the world.
The charity has now confirmed it is feeding one million children a day in 12 countries across four continents, up from the 200 when it first launched in 2002.
One of the children fed every day by the charity, 14-year-old orphan Marita Wyson, was allowed to return to education with the help of the organisation.
She said: "We are so happy to be receiving this food in school! When you feel hungry, it can be difficult just to stand up in the morning. But the phala [the vitamin-enriched maize porridge Mary's Meals serves in Malawi] is making a huge difference.
"It makes me feel strong and I am able to understand what my teachers are telling me. My grandmother doesn't have to worry so much about how she will provide food for me and my sister.
"I am determined to do well at school, because I know how important getting an education is. I have promised my family that I will not fail."
The exact number of children Mary's Meals is now feeding is 1,035,637, across countries including Liberia, Kenya, Zambia, Haiti and India.
Founder and CEO Magnus MacFarlane-Barrow said: "It is quite remarkable to think that a million children are now eating Mary's Meals every school day in some of the world's poorest countries.
"The extraordinary ways in which this work has grown and developed have continually surprised me and filled me with a sense of mystery and awe.
"It would not be true, though, to say that I never expected our work to grow so big. I have long felt that the vision of Mary's Meals - that every child receives a daily meal in their place of education - is so compelling, and people of goodwill so numerous, that it must be fulfilled.
"As I stand here in Malawi today, meeting all the children at Chirimba Primary School who are the latest to receive Mary's Meals, I am struck by the fact that this landmark can be regarded as no more than just 'the first million'.
"With 57 million children out of school today and many millions more around the world chronically hungry, it is clear that our work has only just begun."