Ivian Sarcos, 21, took the ultimate beauty accolade at Earls Court in London, the city where the first Miss World was staged in 1951.
Outside the venue, a small feminist demonstration took place, protesting at what they said was an "appalling offence against women's equality."
The beauty contest was broadcast live to more than 150 countries and was watched by a billion viewers, organisers said.
The competition has drawn criticism in recent years for being outdated and little more than a chance to look good in swimwear.
But of the 122 contestants whom Sarcos beat, a quarter are graduates and more than half speak three or more languages.
Sarcos, who currently works for a broadcasting company, said her future ambition was to work with non-governmental organisations and children, according to the Miss World web site.
She has already created her own foundation to help youngsters.
Her hobbies include volleyball, mountaineering and trekking.
One of 13 children, Sarcos said her proudest moment was "when I did my Communion."
Next year's Miss World will be held in China's Inner Mongolia.