Venezuelan opposition leader María Corina Machado was an obscure candidate just 12 hours before she was announced as winner on Friday.
Some of Trump's Republican allies have called for him to get the Nobel Peace Prize, though the nomination deadline passed early in his current term.
White House decries Nobel Committee's decision not to hand Peace Prize to Donald Trump after Gaza ceasefire deal.
Industrial scion remade herself as a grassroots campaigner bent on unseating President Nicolás Maduro
"When authoritarians seize power, it is crucial to recognize courageous defenders of freedom who rise and resist," the committee said.
María Corina Machado won for her years spent "working for the freedom of the Venezuelan people," according to the Nobel Committee chairman
The opposition politician 'keeps the flame of democracy burning amidst a growing darkness', the Nobel Committee says.
Win dashes hopes of Donald Trump after US president repeatedly claimed he should be awarded prize