Born in 1959 in Haugesund on Norway's west coast, Fosse is best known for his dramas, though his writing spans poetry, essays, children's books and translations.
His work touches on the deepest feelings that you have anxieties, insecurities, questions of life and death, Swedish Academy member Anders Olsson said.
"It has a sort of universal impact of everything that he writes. And it doesn't matter if it is drama, poetry or prose, it the same kind of appeal of basic humanism," Olsson said.
Fosse, seen as a long-time contender for the prize and among this year's favorites in the betting odds, said he was overwhelmed and somewhat frightened by the award.
"I see this as an award to the literature that first and foremost aims to be literature, without other considerations," he said in a statement.
Fosse has spoken extensively of his recovery from alcoholism and a struggle to overcome social anxiety, and the role played by religious faith.
"It's possible to free oneself from alcoholism, but it's hard to transition from a life governed by addiction to one led by something other than alcohol," Fosse said in a Norwegian Salvation Army interview in 2021.
"My conversion (to Catholicism) and the fact that I am a practicing Catholic, has helped me," Fosse said at the time.
The 64-year-old is the fourth Norwegian and the first since 1928 to win the Nobel Prize for literature, this year worth 11 million Swedish crowns (about US$1 million).
"I was surprised but at the same time, in a sense, I wasn't," he told Swedish public broadcaster SVT on Thursday.
"I've been part of the discussion for ten years and have more or less carefully prepared myself for ten years that it could happen."
Past winners of the literature prize include Colombia's Gabriel Garcia Marquez and American John Steinbeck, alongside singer songwriter Bob Dylan and Britain's Second World War Prime Minister Winston Churchill.
Fosse's European breakthrough as a dramatist came with Claude Régy's 1999 Paris production of his 1996 play "Nokon kjem til å komme" ("Someone Is Going to Come").
His magnum opus in prose was the "Septology" series of three books divided into seven parts which he completed in 2021 - "Det andre namnet" ("The Other Name" - 2019), "Eg er ein annan" ("I is Another - 2020), and "Eit nytt namn" ("A New Name" - 2021).
"The work progresses seemingly endlessly and without sentence breaks, but it is formally held together by recurring themes and ritual gestures of prayer in a time span of seven days," the Academy's Olsson said.
Fosse, writes in the least common of the two official versions of Norwegian. He said he regarded the award as recognition of that tongue and the movement promoting it, and that he ultimately owed the prize to the language itself.
Known as "new Norwegian" and used by only about 10% of the population, Fosse's version of the language was developed in the 19th century with rural dialects at its base, making it an alternative to the dominant use of Danish that followed from a 400-year union with Denmark.
"I started writing when I was 12 and the first book was published 40 years ago ... I will keep writing, but I don't plan to compete with myself," Fosse told Norwegian public broadcaster NRK.
Wearing a black leather jacket and sporting his trademark grey pony tail, Fosse said he would not attempt another work as extensive as the Septology and that he planned to celebrate "calmly, with the family. I'll try to enjoy it."
According to his publisher, Fosse's work has been translated into more than 40 languages, and there have been more than 1,000 different productions of his plays.
Since 2011 Fosse has lived at the Grotto, an honorary residence on the premises of Oslo's royal palace that has housed some of Norway's foremost authors and composers in the last century.
Established in the will of Swedish dynamite inventor and businessman Alfred Nobel, the prizes for achievements in literature, science and peace have been awarded since 1901, becoming a career pinnacle in those fields.
The economics prize is a later addition established by the Swedish central bank.
Alongside the peace prize, literature has often drawn the most attention and controversy, thrusting lesser known authors into the global spotlight as well as lifting book sales for well-established literary superstars.
