We find the five Incredibles, aka the Parr family, where we left them last, fighting the Underminer. But he flees in his mini Tunneler. The Incredibles stop the big Tunneler before its destroys the City Hall. Meanwhile, Violet Parr's love interest Tony Rydinger also discovers her superhero identity, forcing agent Rick Dicker to erase his memory. Despite this, the authorities are more concerned with the level of damage caused by the debacle. Dicker informs the Parr family that his department in the Super Relocation program is being shut down as a result of the battle with the Underminer. As a result of this, supers are once again forced to permanently adhere to their secret identities.
Sometime later, a telecommunications tycoon named Winston Deavor of DEVTECH makes contacts with the world's former greatest Super and Bob Parr, his wife Helen Parr, and his best friend Lucius Best, declaring that he wants the Super Relocation Program revoked as much as they do. When, Bob, Helen, and Lucius visit him, Winston proposes a publicity stunt plan in order to gain the general public’s support of supers. In Winston’s plan, Helen Parr, whom Winston considers the least destructive of the supers present, would represent supers as she openly fights crime in the city of New Urbrem. When Bob offers to take care of the kids while she is away, Helen agrees to Winston’s proposal and the Parrs are relocated to an ornate abode provided by Winston.
Bob struggles with his new role as a stay-at-home parent, so his kids have problems of their own. Dash has trouble with math homework, Violet becomes withdrawn after Tony unintentionally fails to show up at their date due to his memory wipe and Jack-Jack wreaks havoc with his burgeoning superpowers. Exhausted, Bob takes Jack-Jack to his old friend, superhero-costume designer Edna Mode, to look after and she agrees upon seeing the baby’s superpowers. Meanwhile, during Helen's mission in New Urbrem, she is confronted by a mysterious villain named the Screenslaver. The Screenslaver hijacks screens to project hypnotic images in order to brainwash civilians.
After Helen rescues an ambassador from the Screenslaver’s clutches, she manages to defeat and unmask the villain, who is revealed to be a pizza delivery man. The pizza delivery man claims that he is at a loss of what was happening. The Screenslaver then tricks Bob into 'rescuing' Helen before the hypnotized heroine forces another pair of hypno-goggles onto Bob, putting him under Evelyn's control as well. Later, Frozone also ends up captured and put under the Screenslaver's control, although the Parr children evade capture themselves. During a celebration at the DevTech, Helen realizes that the hypnoscreens the Screenslaver has made are also within his goggles.
Soon thereafter, the goggles are forced onto Helen by Winston’s sister Evelyn Deavor. Evelyn is the mastermind behind the Screenslaver; stating that she despises superheroes and sees her brother's mission as a threat to humankind's independence. Meanwhile, Dash, Violet and Jack-Jack, in their supersuits, sneak aboard the Everjust, there is a hearing of leaders to re-legalize superheroes. Jack-Jack removes the hypno-goggles on Helen, who then frees Bob and Lucius and reveals Evelyn's plan to the assembled leaders. A battle on the boat ensues threatening to crash the ship into New Urbem. However, the supers manage to stop it and Helen apprehends Evelyn when she tries to make an escape. The supers are thanked and the Supers Relocation Program is finally revoked, making supers legal once again.
After the credits roll, the tunneler of the Underminer (which he escaped in at the beginning of the film) pops out of a hole, which means he has not been caught yet.
- Craig T. Nelson as Bob Parr / Mr. Incredible, who possesses super strength and limited invulnerability.
- Holly Hunter as Helen Parr / Elastigirl, who has the ability to stretch her body into many shapes and forms.
- Sarah Vowell as Violet Parr, the family's daughter and first child, who can become invisible and project force fields for limited lengths of time.
- Huckleberry Milner as Dashiell "Dash" Parr, the family's troublemaker first son, who has superhuman speed. He was previously voiced by Spencer Fox in the first film.
- Eli Fucile as Jack-Jack Parr, the infant son of Bob and Helen who has a large assortment of powers.
- Nicholas Bird provides the vocal effects of Jack-Jack's monster form.
- Samuel L. Jackson as Lucius Best / Frozone, Bob's best friend, who has the ability to form ice from humidity and a new member of the Incredibles.
- Bob Odenkirk as Winston Deavor, a superhero fan who leads a telecommunications company with his sister Evelyn, and wants to bring back the "supers" by revamping the public's perception of them.
- Catherine Keener as Evelyn Deavor, Winston's younger sister, the mastermind behind Screenslaver, and a technological genius who has never encountered a problem she could not solve.
- Bill Wise as a pizza delivery man converted into a villain by the real "Screenslaver", who hijacks screens to project hypnotic images in order to hypnotize civilians.
- Brad Bird as Edna Mode, a fashion designer to the "supers" and a close friend of the Parrs.
- Jonathan Banks as Rick Dicker, a government agent responsible for helping the Parrs stay undercover and unremarkable. When his department is shut down, the Parrs are left to their own devices. He was previously voiced by Bud Luckey in the first film, who died in 2018 and to whom the film is dedicated.
- Michael Bird as Tony Rydinger, Violet's love interest.
- Sophia Bush as Karen / Voyd, a young Elastigirl fan who aspires to be a true superhero, with the power to create wormholes.
- Phil LaMarr as Krushauer and He-Lectrix, two Supers, alongside Voyd, who aspire to be true superheroes. Krushauer has the power of telekinesis while Helectrix has the power of controlling and projecting electrical currents.
- Paul Eiding as Gus Burns / Reflux, an elderly Super (alongside Voyd, Krushauer, and He-Lectrix) who aspires to be a true superhero, with the power of heaving hot lava.
- Isabella Rossellini as The Ambassador, a dignified foreign official committed to the support and legalization of superheroes.
- John Ratzenberger as the Underminer, a mole-like supervillain who seeks to bring war and destruction to the world.
- Charlie Day as Screech (uncredited), a superhero who has owl powers. Day records one line in a whispering voice.
- Cobie Smulders as Concretia "Connie" Mason / Brick (uncredited), a superheroine who has metamorphosis.
- The Outer Limits (orig. 1963-65) - during the scene in which Bob is trying to get Jack-Jack to sleep, the TV plays the opening titles of this show, with the famous lines "We will control the horizontal. We will control the vertical".
- This is an allusion to the team behind the Incredibles, who are controlling our experience (of the movie) for our entertainment, and also an allusion to the Screenslaver who cynically controls the perception of others for his / her entertainment.
- Perception Management - Winston explains how the Incredible's problem is one of perception ('optics' in American parlance): all they need to do is to manage people's perceptions and their problems will disappear.
- This is a classic PR approach to a problem which sees Elastigirl scanning police radio for incidents to respond to in order to create a more favourable public image. It leads to her discovery of the villain, Screenslaver.
- Body-worn Video - one attempted solution to the perception problem is to have cameras built in to the Incredible's costumes. It proves useful in unexpected ways.
- Jonny Quest - After Mr. Incredible wakes up after sleeping seventeen hours, Dash is shown watching the show on television.
- By exploiting the modern human's addiction to screens through hypnotic fascination - "the horizontal" and "the vertical" - the Screenslaver's plan is akin to a story from the Outer Limits.
- It is unknown how the Parr family (minus Jack-Jack), appeared in their supersuits and Jack-Jack being in a stroller as soon the Underminer appeared during Tony's flashback to Dicker, despite that at the end of The Incredibles.They only put their masks on as soon as he appears.
- The Incredibles is the fifth Pixar film to become a franchise, after Toy Story, Cars, Monsters, Inc. and Finding Nemo.
- Bob Odenkirk and Jonathan Banks were both in Breaking Bad and Better Call Saul, as Saul Goodman and Mike Ehrmantraut, respectively.
- Movie theaters posted epilepsy signs about the movie because some scenes contain flashing/strobing lights.
View the movie's transcript here.