She will speak at the United Nations on July 12, said Brown, speaking in his capacity as the UN Special Envoy for Global Education.
Malala was shot at point-blank range by a Taliban gunman as her school bus travelled through Pakistan's Swat Valley on October 9 last year,
She was flown to Britain for surgery on her head injuries and, once she had recovered sufficiently, returned to school in Birmingham, central England last month.
"Malala is a true inspiration and a shining beacon for girls education around the world," said Brown.
"I am full of admiration for her courage and determination in the journey she is on, and am sure that she can become a real leader in the campaign for a school place for every girl -- and every boy."
Malala has become a global symbol of the campaign for girls' right to an education and has been nominated for this year's Nobel Peace Prize.
Some 4,000 young people are expected to be in attendance for her debut speech.
Her self-penned life story is due out later this year in a deal reportedly worth around three million dollars.