Meg Rosoff has won the world’s largest cash prize for children’s literature, the Astrid Lindgren memorial award, honouring the entire body of an author’s work.

Rosoff was one of 215 candidates from 59 countries for the 5m Swedish krona (£430,000) Astrid Lindgren Memorial Award, which goes to work “of the highest artistic quality” featuring the “humanistic values” of the late Pippi Longstocking author. The jury said her seven young adult novels, which include How I Live Now and Just In Case, “speak to the emotions as well as the intellect”, and that “in sparkling prose, she writes about the search for meaning and identity in a peculiar and bizarre world”.

When I saw I had a phone call from Sweden, I actually immediately thought it was telemarketers Meg Rosoff

“Each novel is a little masterpiece,” said chair of the jury Boel Westin. “She says so much in each of them. We’re looking for a writer with the humanistic values of Astrid Lindgren, and Meg Rosoff fulfils that criteria - she has respect for her protagonists and for her readers, she’s discussing how the world can change, but she also gives hope, which I think is important.”

Westin expressed the hope that Rosoff’s views about writing for children - having just published a novel for adults, Jonathan Unleashed, Rosoff told the Guardian that “I think maybe I’ve said mostly what I have to say about adolescence” - might change. “She’s a crossover novelist, but of course we hope that she’ll write more for young adults, because she’s so brilliant,” said Westin.

Informed of her win in a phone call, Rosoff responded: “Oh my God, that’s amazing. I have to sit down – I can’t believe that.”

“When I saw I had a phone call from Sweden, I wish I could say that I immediately thought it was the prize, but I actually immediately thought it was telemarketers,” Rosoff told the Guardian on Tuesday. “There have been so many times that I may have fantasised about winning whatever award, but I never imagined I would win this one.”

Lindgren’s best-known creation Pippi Longstocking was “absolutely a hero of mine when I was a kid, because she was a maverick,” said Rosoff. “I was told my whole life that I needed to be a nice girl, and then there’s Pippi in huge boots carrying a horse around. I couldn’t have had a better hero.”

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Nominated for the prize in the past, Rosoff has previously said that being on the longlist was “like being invited to join an exclusive worldwide club”, but that “I wouldn’t say I’m exactly worrying about spending the money”. After winning the award, Rosoff said she couldn’t “even think about the money – I know I want to give a lot of it away, but I’m not sure to whom yet”.

Rosoff also admitted that the win was likely to make her reassess her plans to stop writing for children. “It’s an extraordinary sense of affirmation. I do genuinely believe, and I tell my students, that your job as a writer is not to read reviews or Goodreads or to be on Twitter drumming up business, but to write books. The goal of writing is to write, not to pay attention to accolades. But on the other hand, it does make a difference,” she said.

“It feels amazing. I can’t get over it. My last two books in the UK weren’t even shortlisted for the Carnegie [book prize] ... so it’s really nice to have affirmation from the international community, especially when so many people on the list are either madly famous, or who I just admire so much.”

Rosoff was born in the US, and has lived in London for years. Her first novel, How I Live Now, about a teenage New Yorker and her English cousin set as world war three breaks out in London, was written while she was working in advertising. She resigned as soon as she sold the manuscript, and it won several prizes, including the Guardian children’s fiction award. It was adapted for film in 2013.

The Astrid Lindgren jury praised Rosoff’s “richly varied” career, including her 2006 novel Just in Case, for which she won the Carnegie prize, and What I Was (2007), an exploration of gender and identity on the East Anglian coast during the 1960s.

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“Like Astrid Lindgren, Rosoff empathizes completely with young people and is utterly loyal to them,” said the jury in its citation. “The adult world, when it appears, remains on the periphery. She uses concrete, vibrant language, whether she is describing a landscape, a piece of clothing, or the groceries in the pantry. She infuses darkness with humour to produce stylistic masterpieces.”

The Astrid Lindgren memorial award was founded in 2002 by the Swedish government, and has been won in the past by Shaun Tan, Maurice Sendak and Philip Pullman. Rosoff will be presented with her award on 30 May in Stockholm.