Olivia Culpo from Rhode Island makes it an eighth victory for the USA after beating Miss Philippines -23-year-old Janine Tugonon.
The new Miss Universe beat 88 contestants from from other countries at the pageant held in Las Vegas.
Culpo will spend the next year travelling the world representing the Miss Universe Organisation and a charity of her choice.
She was chosen by a 10-judge panel who considered contestants representing countries ranging from India to Kosovo and Britain.
Miss Philippines, 23-year-old Janine Tugonon, was the runner-up and Miss Venezuela, Irene Sofia Esser Quintero, came third after the top five answered brief questions posed by the judges.
Culpo takes the place of last year’s winner Leila Lopes, who was the first ever Miss Universe from Angola.
Contestants must be aged between 18 and 27, unmarried and with no children.
The contest was broadcast live on US television from the Planet Hollywood hotel and casino in Las Vegas and seen by an estimated one billion viewers on TV and online in 190 countries, organisers said.