Albert Markovski (Jason Schwartzman) is a young man who heads the local chapter of an environmental group, the "Open Spaces Coalition". One of their current projects is an attempt to stop the building of a new Huckabees store, a chain of "big-box" department stores. Albert is a rival of Brad Stand (Jude Law), a shallow power executive at Huckabees. Brad infiltrates Open Spaces and charismatically displaces Albert as the leader. Dawn Campbell (Naomi Watts) is Brad's live-in girlfriend and the face and voice of Huckabees; she appears in all of the store's commercials.
After seeing the same conspicuous stranger three times, Albert contacts two existential detectives, Bernard (Dustin Hoffman) and Vivian Jaffe (Lily Tomlin). The detectives offer Albert their optimistic brand of existentialism—they name it universal interconnectivity (which has some tenets of romantic and transcendentalist philosophies)—and spy on him, ostensibly to help him solve the coincidence. Bernard and Vivian introduce Albert to Tommy Corn (Mark Wahlberg), an obsessively anti-petroleum firefighter. Tommy is assigned to Albert as his 'other'.
Tommy grows dissatisfied with the Jaffes, feeling that they are not helping him. Seeking out other possibilities, Tommy ends up abandoning and undermining the Jaffes by introducing Albert to Caterine Vauban (Isabelle Huppert), a former student of the Jaffes who espouses a seemingly opposing nihilistic/absurdist philosophy. She teaches them to disconnect their inner beings from their daily lives and their problems, to synthesize a non-thinking state of "pure being." Being lifted from their troubles, they wish to keep that feeling forever, yet she tells them that it is inevitable to be drawn back to the human drama, and to understand that the core truth of that drama is misery and meaninglessness. In order to prove her point, Caterine takes Albert to go and have sex in the woods, leaving Tommy behind. Tommy finds out about the two of them being together and feels hurt. Caterine tells him that they found each other through all of the human suffering and drama. Tommy rejects this idea and leaves them furious and lost. Meanwhile, in Brad's further attempts to undercut Albert, he and Dawn meet with and are influenced by Bernard and Vivian. In the following days, Brad and Dawn rethink their entire lives: Dawn rejects the modeling world and looks for deeper meaning, and Brad realizes that his whole ascent on the corporate ladder is meaningless, as he has lived his whole life just trying to please others and not himself.
All the storylines collide when Brad's house catches fire. While the fire trucks get stuck in a traffic jam, Tommy comes on his bicycle to put out the fire, which incidentally trapped Dawn inside. As he saves her life, the two fall in love. Meanwhile, Brad despairs at the destruction of his house, the symbol of his material success. Albert attains a sort of enlightenment when he synthesizes the two opposing outlooks of the Jaffes and Vauban to realize the cosmic truth of everything. Brad, meanwhile, is fired from Huckabees, leaving him rudderless. Albert reveals to Brad that he burned Brad's jet skis, and the fire spread to the house. Albert understands that he and Brad are no different, that everything really is inextricably connected, but that these connections necessarily arise from the often senselessly painful reality of human existence. Having realized this, he refers Brad to Caterine, hoping she will help him as she did Albert and Tommy. Albert and Tommy talk later about everything that has happened. As the two talk, Caterine and the Jaffes watch them, concluding that they can close both of their cases.
In an interview with the SuicideGirls website, director Russell said in response to the question "How do you describe I Heart Huckabees?":
Before directing his first feature, Spanking the Monkey, Russell intended to make a film "about a guy who sits in the back of a Chinese restaurant with microphones on every table to surreptitiously listen to everybody’s conversations, then write perversely personal fortunes for each of the people." Hitting a writer's block, Russell could not figure out how to make the film work. In the meantime Russell was called for jury duty, after which he stopped writing the film. Ideas in the script stayed with him though and they would later form the basis for the Huckabee script. The final idea came to Russell in a dream where "This female detective she was not following me for criminal reasons, but she was following me for spiritual and metaphysical reasons." Russell, who makes a habit of writing his dreams down, knew instantly upon reading his summary of the dream that this was the story he wanted to pursue.
In March 2007, two videos were leaked onto YouTube portraying on-set arguments between Russell and Tomlin, in which among other things he called her sexist names. When the Miami New Times asked Tomlin about the videos, she responded, "I love David. There was a lot of pressure in making the movie—even the way it came out you could see it was a very free-associative, crazy movie, and David was under a tremendous amount of pressure. And he's a very free-form kind of guy anyway."
In an advertising campaign for the film, four fictional websites were created. They were portrayed as if they were actual websites involving the characters and organizations featured in the film. Each website had a link called "Disclaimer" at the bottom that leads to FOX Searchlight's official website for the film. Websites were rendered inactive a few months after release, each now redirecting to FOX Searchlight's website.Huckabees Corporation: The "official" website for the chain of Huckabees stores. Featured the store history, announcements, three television ads featuring Dawn Campbell, and a banner promoting the Huckabees collaboration with the Open Spaces Coalition.
Open Spaces Coalition: This website described the importance of the marshlands Albert Markovski is trying to protect, ways of aiding the cause. The site also contained poetry written by Markovski and downloadable flyers.
Existential Detectives: The website promoting the Jaffes' detective agency. It explained the methodology of the detectives, had two case studies and an online questionnaire.
Caterine Vauban: The website of Caterine Vauban, author of "If Not Now". The site contained reviews and excerpts from the book.
I Heart Huckabees opened in a limited release on October 1, 2004, earning $292,177 and ranking number 24 in the weekend's box office. The film was granted a wide release three weeks later on October 22, earning $2,902,468, ranking tenth in the box office. At the end of its run, the film grossed $12,785,432 domestically and $7,286,740 overseas for a worldwide total of $20,072,172.
The film received mixed to positive reviews from critics. Review aggregator website Rotten Tomatoes gives the film a 62% rating based on 187 reviews. Metacritic reports a 55 out of 100 rating based on 40 critics, indicating "mixed or average reviews".
Some critics were displeased with the existential subject matter and said the script was unfocused, while others celebrated its performances (especially Wahlberg as Tommy Corn) and originality.
Jon Brion provided the score and seven original songs for the film. His unique methods for writing previous film scores (Punch-Drunk Love, Eternal Sunshine of the Spotless Mind) involved very close collaboration with the director. Through this process, David O. Russell was able to sit in the same room with Brion and watch an early cut of the film. Russell described what he wanted to portray and Brion would compose music to Russell's descriptions. The process can be seen on a featurette on the film's special edition DVD.
David O. Russell, while working with Brion, had come across Brion's first solo album, Meaningless. Russell has mentioned that Brion's album asks similar questions to the ones Russell was trying to ask with I Heart Huckabees. In particular, Russell notes that the questions on Meaningless are closer to the questions directed from Caterine Vauban's negative and dark point of view.
Many cues used in the film feature a Chamberlin, a keyboard instrument from the 1950s that replicates instrumental sounds using recorded tape.