It honoured the 67-year-old "for her polyphonic writings, a monument to suffering and courage in our time."
Alexievich has drawn international acclaim with her emotional accounts of the Chernobyl disaster and World War II based on witness accounts.
Chronicling such horrors in the first person through the words of witnesses, Alexievich has seen her works translated into numerous languages and scooped international awards.
But her books, controversially written in Russian, are not published in her home country, long ruled by authoritarian President Alexander Lukashenko, amid what the author has described as "a creeping censorship".
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The Nobel awards week continues tomorrow with the other most closely-watched Nobel award, the peace prize.
The economics prize will wrap up this year's Nobel season on October 12.
The laureates will receive their prizes at formal ceremonies in Stockholm and Oslo on December 10, the anniversary of the 1896 death of prize creator Alfred Nobel, a Swedish philanthropist and scientist.