Pippi Longstocking quickly became popular in Sweden upon publication, and by the end of the 1940s, 300,000 copies had been sold, saving Rabén and Sjögren from impending financial ruin. This was partially due to Olenius's marketing: she ensured that the book was frequently read to a radio audience, as well as helping to put on a popular adaptation of the book at her children's theatre at Medborgarhuset, Stockholm, in March 1946, for which only a library card was required for admission. This performance also toured other Swedish cities, including Norrköping, Göteborg, and Eskilstuna. Another factor in the book's success was two positive reviews by the influential Swedish critics of children's culture, Eva von Zweigbergk and Greta Bolin, writing for Dagens Nyheter and Svenska Dagbladet, respectively; they praised the main character as "a liberatory force." Zweigbergk wrote that Pippi could provide an outlet for regular children who do not have the considerable freedom she possesses, with which Bolin agreed, remarking that Pippi's humor and antics would also appeal to adults for the same reason.
Subsequent reviews of Pippi Longstocking echoed the general opinions of von Zweigbergk and Bolin towards the book, until John Landquist's criticism in an August 1946 piece published in Aftonbladet, titled "BAD AND PRIZEWINNING." Landquist, who worked as a professor at Lund University, argued that the book was badly done, harmful to children, and that Pippi herself was mentally disturbed. Further criticism of Pippi's supposedly "unnatural" and harmful behavior followed in an article in the teachers' magazine Folkskolläranas Tidnung and in readers' letters to magazines. This debate over Pippi's performance of childhood colored the reviews of the sequel Pippi Goes On Board (October 1946), some of which responded to Landquist's argument within the review itself. Regardless, Pippi continued to maintain her popularity and was featured in a range of merchandising, adaptations, and advertising.
In 1950, Pippi Longstocking was translated into American English by Viking Books, one of the few translations of children's literature there, and did not become a bestseller, although sales did eventually improve after the initial release; more than five million copies had been sold by 2000. Pippi was positively received by American reviewers, who did not find her behavior "subversive" or problematic, but rather "harmless" and entertaining. Eva-Maria Metcalf has argued that Pippi was subject to a "double distancing" as both a foreign character and one believed to nonsensical, thus minimizing her potentially subversive actions that had stirred the minor controversy earlier in Sweden. As a result of Pippi and Lindgren's growing recognition in the United States, Pippi's behavior became more critically scrutinized by literary critics, some of whom were less sure of the "hilarious nonsensical behavior, the goodness of her heart, and the freedom of her spirit" that had been lauded in earlier reviews. Reviewers of Pippi in the South Seas in Hornbook and The Saturday Review found Pippi to be less charming than in earlier books, with The Saturday Review describing her as "noisy and rude and unfunny."
In the twenty-first century, Pippi has continued to maintain her popularity, often placing on lists of favorite characters from children's literature or feminist characters. She appears as a character in Astrid Lindgren's World, a theme park in Vimmerby, Sweden, dedicated to Lindgren's works, and on the obverse of the Swedish 20 kronor note, as issued by Riksbank. Additionally, Pika's Festival, a children's festival in Slovenia, borrows its name from her. Pippi has also inspired other literary creations: for his character Lisbeth Salander in the Millennium series, Stieg Larsson was inspired by his idea of what Pippi might have been like as an adult. Pippi has continued to remain popular with critics, who often cite her freedom as part of her appeal. The Independent's Paul Binding described her as "not simply a girl boldly doing boys' things," but rather "[i]n her panache and inventiveness she appeals to the longings, the secret psychic demands of girls and boys, and indeed has happily united them in readership all over the world." Susanna Forest of The Telegraph called Pippi "still outrageous and contemporary" and "the ultimate imaginary friend to run along rooftops and beat up the bad guys." In 100 Best Books for Children, Anita Silvey praised the character as "the perfect fantasy heroine — one who lives without supervision but with endless money to execute her schemes."
The character has also centered in debates about how to handle potentially offensive racial language in children's literature. In 2014, the Swedish public broadcastor SVT edited the 1969 television adaptation of Pippi Longstocking with the approval of Astrid Lindgren's heirs: the first removed Pippi's reference to her father as "King of the Negroes," a term now offensive in Sweden;[nb 1] and the second eliminated Pippi slanting her eyes, although it kept her pretending to sing in Chinese. These changes received a backlash: of the first 25,000 Swedish readers polled by the Aftonbladet on Facebook, eighty-one percent disagreed with the idea of removing outdated racial language and notions from Pippi Longstocking, and the columnist Erik Helmerson of Dagens Nyheter labelled the changes as censorship. One of Lindgren's grandchildren, Nils Nyman, defended the edits, arguing that to not do so might have diluted Pippi's message of female empowerment.