Here are top five facts about the new incoming leader:
Ms Truss will become the UK's third woman prime minister following Theresa May and Margaret Thatcher.
She began her political journey as a teenage member of the centrist Liberal Democrats before switching to the right-wing Conservatives.
In 2016, she campaigned for the UK to remain in the European Union but quickly switched allegiance when Britons backed Brexit.
Truss became foreign minister a year ago after holding a series of ministerial posts in departments including education, international trade and justice.
Her sartorial sense and love of photo opportunities - posing in a tank in Estonia and wearing a fur hat in Moscow - have earned her comparisons to Tory icon Thatcher. She also loves karaoke and socialising.
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