The film was produced by Nickelodeon Movies, Snee Oosh, Inc., and Nickelodeon Animation Studios, and was released on June 28, 2002 by Paramount Pictures. It was the second film made by Nickelodeon Movies to be based on a Nicktoon.
Arriving home from a basketball game, Arnold, and his best friend, Gerald, learn that Scheck, the CEO of FutureTech Industries (FTI), has announced plans to redevelop the entire neighborhood as a luxurious high-rise shopping mall. That night, Helga finds out that her father, Big Bob, is working with FTI to build a new super-sized branch of his beeper store in the proposed mall. She ultimately sides with her father, though becomes hesitant to do so, because of her love for Arnold.
Arnold hosts a protest rally against FTI. Unfortunately, their permit is stolen by Scheck's employees, Grandma Gertie is arrested, and the protest is subsequently declared illegal. The failure encourages many of Arnold's neighbors to surrender, and sell their homes to FTI. As the residents begin packing their belongings, Grandpa Phil tells the story of the "Tomato Incident", a major revolutionary war battle fought in the city. Arnold realizes that the neighborhood had to have been declared a historic district after the war, effectively ensuring its preservation, but the legal document granting its landmark status had been sold to a collector, who is none other than Scheck himself. When confronted, however, he denies having the document, and orders Arnold and Gerald out of his office.
As the deadline draws near, Arnold gets a mysterious phone call from "Deep Voice" (a "Deep Throat"-esq character), who informs Arnold that Scheck is lying, and the document is in his office is safe. Arnold and Gerald manage to steal the key to the safe from Scheck's assistant, Nick Vermicelli. Nick later notices the missing key, and informs Scheck. Meanwhile, Phil and the boarders try to devise a backup in case Arnold fails. The plan is to wire the storm drain tunnels beneath their street with dynamite to intercept FTI's construction equipment. Big Bob later teams up with them, after discovering that Nick's contract states Scheck will control 51% of his company, and swindle him as a result.
With help from agent Bridget, Arnold and Gerald sneak into FTI headquarters, and access the safe, only to find out that the document is not there. Scheck appears from behind them, with the document in his possession. He reveals that his ancestor, a governor of the British forces, was humiliated by the "Tomato Incident", and, that, for years, Scheck was planning to avenge his family by tearing down that very neighborhood, and replacing it with a hulking building, carrying his name on it. He then burns the document to ensure that his plans will proceed, before summoning his guards to again remove Arnold and Gerald. They manage to escape, but believe they have failed, until "Deep Voice" advises Arnold to obtain the FTI's security-camera footage of Scheck burning the document.
After Arnold finds out that "Deep Voice" is Helga, he asks why she decided to help him instead of her father. Helga reluctantly confesses her love, and then kisses Arnold. Helga and Arnold escape the building, and meet Gerald on a city bus, convincing the driver to race home when realizing that his girlfriend lives in the same neighborhood. Despite several near-collisions, the kids eventually returned unharmed. The Mayor arrives at the scene, along with the police, and a news crew. Accessing the large ScheckVision monitor poised atop a nearby building, Arnold and Bridget show everyone the footage of Scheck burning the document. The Mayor officially restores the neighborhood's status as a historic site.
Scheck arrives, demanding to know why the demolition has not begun. He sees the footage of himself burning the document on the monitor. Gertie, having escaped prison, sabotaged his car, and Scheck is promptly arrested. Harold accidentally sits down on the detonator that ignites Phil's explosives. But explosives beneath the street destroy the ScheckVision monitor instead. Helga denies ever having loved Arnold, claiming that she said those things in "the heat of the moment". Arnold, unconvinced, pretends to accept it. Eugene sings about the neighborhood being saved until Gerald interrupts him.
In 1998, the Nickelodeon cable network renewed the original Hey Arnold! series for a fourth season, and gave creator Craig Bartlett the chance to develop two feature-length adaptations. As work on the fifth season was completing, in 2001, Bartlett and company engaged in the production of the first film, titled Arnold Saves the Neighborhood. The Neighborhood project was originally considered for television and home video, but eventually became Hey Arnold!: The Movie when executives at Paramount Pictures decided to release it theatrically after successful test screenings. According to animation historian Jerry Beck (in his Animated Movie Guide), the decision was also buoyed by the financial success of the first two Rugrats films, The Rugrats Movie and Rugrats in Paris: The Movie. A sequel was in production called Hey Arnold!: The Jungle Movie, despite the disappointing results of the first film, Nickelodeon still wanted to release the Jungle Movie the following year, unfortunately, the project was cancelled due to Bartlett walking out on the project and left Nickelodeon resulting in Hey Arnold's cancellation. In 2015 however, it was announced that the movie has been revived and is currently in production as a TV movie expecting to be released in late 2017.
The first trailer was released during the 2002 Kids' Choice Awards. They showed segments on Nickelodeon called "Backyard Players" where kids would play Arnold, Gerald, and Helga and act out scenes from the film. There was a contest held for a lucky winner to be Arnold for a day and go to the film's premiere. The song "2-Way" by Lil' Romeo, featuring Master P, was used to help promote the movie.
Hey Arnold!: The Movie was Nickelodeon's first animated feature to receive a PG rating from the Motion Picture Association of America (MPAA) for thematic elements.
Opening on June 28, 2002 in the United States, the film grossed over $15 million worldwide on a budget of $3 million. The film grossed $5.7 million from 2,500 theaters on its opening weekend, ranking sixth in the box office and second in the week's new releases, behind Mr. Deeds. The film grossed $13.7 million domestically and $1.5 million internationally for a worldwide total of $15.2 million.
The film received mixed to negative reviews. It scored a 29% approval rating on Rotten Tomatoes based on 78 reviews with the following critical consensus: "Bland, unoriginal and lacking the wit of the TV series, Hey Arnold! is a 30-minute cartoon stretched beyond its running time." Metacritic recorded a score of 47/100 based on 23 reviews, indicating "Mixed or average reviews". The film received some positive reviews such as those at the New York Post, the San Francisco Chronicle and Entertainment Weekly.
The film was released on VHS and DVD on December 31, 2002 (New Year's Eve); its special features consisted of only the theatrical trailer and an interactive game based on Charlotte's Web 2: Wilbur's Great Adventure. The film has also been available for streaming on the internet service Netflix.
THQ released a video game of the movie, exclusively for the Game Boy Advance. The game consists of five worlds, with four levels each (each including a boss on the fourth level) and the player can play as Arnold, Gerald, Grandpa, and Grandma. Helga is playable only with a cheat code found on various websites.
A direct-to-TV sequel, Hey Arnold!: The Jungle Movie, is planned to be released around November 2017.