Michael Nott, who is in the second year of a Btec national certificate in photography at City of Westminster college, won the pound;3,000 Joan Wakelin bursary.
The money will enable him to return to Cambodia to complete his project documenting the lives of Aids victims and orphaned children.
Photographer Don McCullin, one of the judges, said: "Michael's work stood out. For someone so new to documentary photography his HIVAids work shows a determined commitment to this difficult subject, along with a clear compassion for the people he photographs."
Mr Nott, a secondary school teacher, started taking photographs in Cambodia while visiting his sister, who works for an HIVAids charity there.
He said: "I was really interested - I've been out to Cambodia three or four times. I wanted to do a project over the summer to show how people live there.
"The vast majority of kids in the orphanage had been orphaned by Aids. I couldn't stop taking pictures and got completely hooked."
His next trip to complete the project will be over Christmas and the pictures will appear in the Royal Photographic Society journal in spring next year.
Mr Nott. 32, from south London, said: "The facilities are fantastic, the teaching is good and the course is really well-organised." He is now considering whether he might make a career in photography.
Andrew Robertson, his lecturer, said the course focused on helping talented photographers to produce work that they could sell as well as introducing them to new types of equipment.
He said: "Michael can go as far in photography as he can commit to. If you look at the people he beat for the award, most of them are starting to do professional commissions. He could certainly make a living from it."