Nel-Peters is from the South African coastal community of Sedgefield in the Western Cape province.
Miss Colombia Laura González and Miss Jamaica Davina Bennett came close and took the first and second runners up spots, respectively.
Nel-Peters, a graduate in business management, said her disabled half-sister has been among her great inspirations.
"Women earn 75% of what men earn doing the same thing". REUTERS/Steve Marcus Miss South Africa Demi-Leigh Nel-Peters poses for photos following the 66th Miss Universe pageant at Planet Hollywood hotel-casino in Las Vegas, Nevada, U.S. November 26, 2017. Like each year, the sparkling silver and blue gem encrusted crown was passed on to the new Miss Universe by last year's victor Miss France Iris Mittenaere.More news: Ridiculously cheap Samsung Galaxy S8 price for White Friday
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The second runner-up was miss Jamaica and the first runner-up was Miss Columbia.
Host Steve Harvey poked fun at his 2015 botched Miss Universe crowning throughout the night.
Nel-Peters accepts her crown from her doppelganger, basically - Iris Mittenaere, Miss Universe 2016 (and previously Miss France). As India's Manushi Chhillar won the Miss World title 17 years later, hopes were pinned on India's Miss Universe candidate Shraddha Shashidhar, who sadly could not make it to the top 16. The contestants have been touring, filming, rehearsing and preparing to compete for the Miss Universe crown in the Philippines.