Kevin Brooks picked up the Carnegie Medal for his novel The Bunker Diary after more than a decade spent trying to get it published.
He said he resisted attempts to re-write the book and said young readers were "perfectly capable" of dealing with "complex and serious stuff".
He said: "They're not babies, they don't need to be told not to worry, that everything will be all right in the end, because they're perfectly aware that in real life things aren't always all right in the end."
Brooks, who worked as a hot dog seller at London Zoo and sieved ashes at a crematorium before finding success as an author, lives in North Yorkshire and has written more than a dozen books.
Accepting the award, formally known as the Cilip Carnegie Medal, he said: "I knew I could have got the book published earlier if I'd changed the ending and made some other changes - toned it down, explained a lot of unexplained things - but to me that would have meant writing a different book, a book that I didn't want to write."
The winner receives a gold medal and £500 of books to donate to a library of their choice, which Mr Brooks gave to the library in Pinhoe, near Exeter, where he grew up.
The medal, which counts CS Lewis and Philip Pullman among its former winners, was founded in 1936 in memory of Scottish-born philanthropist Andrew Carnegie and is judged by librarians.
The Kate Greenaway Medal, given for illustration, was awarded to Jon Klassen for This is Not My Hat about a thieving fish.
Helen Thompson, who chaired the judging panel, said: "Children and teenagers live in the real world; a world where militia can kidnap an entire school full of girls, and where bullying has reached endemic proportions on social media. Exploring difficult issues within the safe confines of a fictional world creates essential thinking space, and encourages young people to consider and discuss their own feelings and reactions. I believe that the books being published for children and young people are often better researched, better written and more thought provoking than most adult books, and this year's Cilip Carnegie and Kate Greenaway books are no exception."