Kinney spent eight years working on the first book before showing it to a publisher. In 2004, Funbrain and Kinney released an online version of Diary of a Wimpy Kid. The website made daily entries from September 2004 to June 2005. The online version had received almost 20 million views by 2009. Nonetheless, many online readers requested a printed version. In February 2006, during the New York Comic Con, Kinney signed a multi-book deal with publisher Abrams Books to turn Diary of a Wimpy Kid into a printed book series. The first installment was released in April 2007 and received immediate success. In April 2009, Time magazine named Kinney in the Time 100 most influential people.

As of October 2024, the series consists of nineteen main entries, as well as an activity book. A spin-off series centering on the character Rowley Jefferson has three installments as of 2021. 20th Century Studios produced a live-action film series of the same name from 2010 to 2017, and three animated films in the early 2020s.

Since the release of the online version, most of the books have garnered positive reviews and commercial success. As of 2020, more than 250 million copies have been sold globally, making it the fourth best-selling book series of all time.

• Diary of a Wimpy Kid Do-It-Yourself Book is an activity book that features a blank section encouraging readers to keep their own journal in the style of the books.
  • The Wimpy Kid Do-It-Yourself Book (published after the second edition of Wimpy Kid Movie Diary and before Cabin Fever) is the same book as the first Do-It-Yourself Book, but with 60 extra pages and 16 more full-color comics.
• The Wimpy Kid Movie Diary is a book about the making of the first film, which features stills and brand-new illustrations. Jeff Kinney dedicated the book to the film's main stars, Zachary Gordon and Robert Capron.
  • The Wimpy Kid Movie Diary: Now Includes The New Movie Rodrick Rules is an updated version of the first book, now featuring stills from the second film Rodrick Rules, more new illustrations, and information on how the second film was made.
  • The Wimpy Kid Movie Diary: The Story of All 3 Movies! is the second updated version of the first book, now adding stills from the third film Dog Days, and information on how this film was made.
• The Wimpy Kid Movie Diary: The Next Chapter covers how the film The Long Haul was made. It is dedicated to Jason Drucker, the actor who played Greg in that movie.

A spin-off series has been published, written from Rowley's perspective. The first installment, Diary of an Awesome Friendly Kid: Rowley Jefferson's Journal, was released on April 9, 2019, and is a series of anecdotes about Greg and Rowley's friendship. The second, Rowley Jefferson's Awesome Friendly Adventure, is in the style of a fantasy adventure and was released on August 4, 2020. The book's original release date was April 7, 2020, but was delayed due to the COVID-19 pandemic. The third, Rowley Jefferson's Awesome Friendly Spooky Stories, was released on March 16, 2021.

Audiobooks have been released for each main installment in the Diary of a Wimpy Kid series. The Recorded Books versions are read by Ramon de Ocampo, while the Penguin Books versions are read by Dan Russell, who has done so since The Third Wheel, and in 2018 he re-narrated the first 6 books for the markets where Penguin publish the series.

• Greg Heffley is a middle school student, who is the main character and narrator of the series. He is an anti-hero, described by Kinney as "cocksure" and "misguided".
• Rowley Jefferson is Greg's good-natured best friend.
• Rodrick Heffley is Greg and Manny's older brother, who is rude, and the drummer in his band Löded Diper. He usually is noted for playing tricks on Greg.
• Manny Heffley is Greg and Rodrick's spoiled younger brother, who is known to be a tattletale.
• Susan Heffley is Greg's mother. She often embarrasses Greg.
• Frank Heffley is Greg's father. He always wants Greg to do sports and "to become a man", and doesn't like giving up.
• Gramma is Greg's maternal grandmother.
• Grandpa is Greg's paternal grandfather who is sometimes noted for irritating Greg.
• Fregley is Greg's odd neighbor and classmate.
• Chirag Gupta is one of Greg's friends whom he once played a trick on, pretending Chirag to have been invisible, then later pretended he was going deaf.
• Holly Hills is Greg's crush.
• Heather Hills is Holly's sister, and was Greg and Rodrick's crush.
• Patty Farrell is Greg's rival in school.
• Sweetie is the name given to the Heffleys' temporary dog, who annoys Greg. Later on, they give him to Gramma, who spoils him and is the cause of him becoming overweight.
• An unnamed pig was won by Manny at a county fair. The pig displays high intelligence, and walks upright. In The Getaway, the family put the pig in a kennel while they went on vacation but the pig escaped and hasn't been seen again.

• Albert Sandy is a kid in Greg's grade who always tells untrue rumors, usually meant to scare the other children.

Diary of a Wimpy Kid was well received from The Princeton Review, Gold Card Association, The Dallas News, The TRR Editors, The NW Press, and The JJ Printing Company. The New York Times, which ranks children's serials collectively on a "Series Books" bestseller list, has included the Wimpy Kid series for 812 weeks as of October 14, 2024. USA Today, which ranks best sellers based on sales alone regardless of genre or intended audience, has listed Diary of a Wimpy Kid in its top 150, peaking at number 8, for 141 weeks as of April 4, 2010.

As of the same date, Rodrick Rules has been on the list for 117 weeks (peaking at number 4), The Last Straw has been on the list for 65 weeks (peaking at number 1), Dog Days has been on the list for all 25 weeks of its publication (peaking at number 1), and The Wimpy Kid Movie Diary has been listed for all three weeks of its publication, peaking at number 2.

The series has sold over 200 million books in 56 languages and 65 editions throughout the world. The series has also generated over $500 million in revenue.

On March 14, 2011, Jeff Kinney published a video game adaptation of Diary of the Wimpy Kid, entitled Wimpy Wonderland Island, to his online role-playing video game Poptropica as one of the main "island" levels, in which the player must problem-solve through game quest scenarios, centering on a problem that the player must resolve by going through multiple obstacles, collecting and using items, talking to various characters, and completing goals. On July 3, 2012, Kinney published a second game, entitled Wimpy Boardwalk Island.

Jeff Kinney announced that a film based on the first book would be produced by 20th Century Fox. The film was released on March 19, 2010, moved up from an April 2 release date. It was directed by Thor Freudenthal, who also directed Hotel for Dogs. The film starred Zachary Gordon as Greg, Robert Capron as Rowley (Greg's best friend), Steve Zahn as Frank (Greg's father), Rachael Harris as Susan (Greg's mother), Devon Bostick as Rodrick (Greg's older brother), Connor and Owen Fielding as Manny (Greg's younger brother), Chloë Grace Moretz as a new character named Angie, and Grayson Russell as Fregley.

The second film in the Diary of a Wimpy Kid film series, which was released on March 25, 2011, was based on the second book Rodrick Rules, with Zachary Gordon reprising his role as Greg Heffley. The film also contains some elements from The Last Straw within its plot.

The third film combines the third and fourth books The Last Straw and Dog Days, taking stories from both, but mainly from Dog Days, from which it took its title. The decision to blend the two films was made to keep up with the ages of the actors. The film was released on August 3, 2012.

The likelihood of a fourth live-action film was slim. Kinney has announced the possibility for an animated film to be based on Diary of a Wimpy Kid: Cabin Fever as the next installment. In an interview for the book Hard Luck, Jeff Kinney stated he was working with Fox on a half-hour special of Cabin Fever, which was to be aired in late 2014, but as of 2021 no updates on the special have been announced. In September 2016, Jeff Kinney announced officially the production of a fourth film, Diary of a Wimpy Kid: The Long Haul, on his Twitter account. The film was released on May 19, 2017 and was based on The Long Haul.

On August 6, 2019, Disney announced they would reboot Diary of a Wimpy Kid, Home Alone and Night at the Museum for their streaming service, Disney+. On December 10, 2020, Disney announced at their 2020 Investor's Day that an animated Diary of a Wimpy Kid film would be coming to Disney+ on December 3, 2021.

A second animated film, Diary of a Wimpy Kid: Rodrick Rules, was released to Disney+ on December 2, 2022.

A third animated film, Diary of a Wimpy Kid Christmas: Cabin Fever, was released to Disney+ on December 8, 2023.

Diary of a Wimpy Kid: The Musical was produced by the Children's Theatre Company in 2016. The company staged a reworked version of the production in 2022. A studio album of songs from the show recorded by Broadway performers such as Sutton Foster and Norbert Leo Butz was released on December 14, 2023. Broadway Licensing Global offers licensing materials for professional and amateur productions of the musical.

• Official website
• Online book Archived November 19, 2016, at the Wayback Machine on Funbrain
• Official blog
• Official film site