The Nobel Prize for literature has been awarded to US poet Louise Gluck "for her unmistakable poetic voice that with austere beauty makes individual existence universal".
The prize was announced on Thursday in Stockholm by Academy Permanent Secretary Mats Malm.
He said Gluck was "surprised and happy" at the news despite receiving it early morning North American time.
A professor at Yale University, Gluck, 77, made her debut in 1968 with Firstborn.
She is seen as one of the most prominent poets in US contemporary literature.
Her poetry is characterised by "a striving for clarity", the Academy said, with a focus on childhood, family life, and close relationships between parents and siblings.
"In her poems, the self listens for what is left of its dreams and delusions and nobody can be harder than she in confronting the illusions of the self," the Academy said.
Gluck, who shuns publicity, had no immediate comment.
In a 2012 interview with the Academy of Achievement, she noted that "worldly honour makes existence in the world easier" but said her true goal as an artist was "not capable of being had in my lifetime".
"I want to live after I die, in that ancient way," she said.
"And there's no way of knowing whether that will happen, and there will be no knowing, no matter how many blue ribbons have been plastered to my corpse."
The awarding of the prize follows several years of controversy and scandal for the world's pre-eminent literary accolade.
In 2018 it was postponed after sex abuse allegations rocked the Swedish Academy, the secretive body that chooses the winners, and sparked a mass exodus of members.
After the academy revamped itself in a bid to regain the trust of the Nobel Foundation, two laureates were named last year, with the 2018 prize going to Poland's Olga Tokarczuk and the 2019 award to Austria's Peter Handke.
Handke's prize caused a storm of protest: a strong supporter of the Serbs during the 1990s Balkan wars, he has been called an apologist for Serbian war crimes.
Several countries including Albania, Bosnia and Turkey boycotted the awards ceremony in protest and a member of the committee that nominates candidates for the literature prize resigned.
This year it was expected the academy would seek a more harmonious choice for the 10 million kronor ($A1.5 million) prize.