In the opening of the film, the Joker and his men hijack a plane containing several tons of explosives, planning on using them to destroy Gotham City. When the pilot of the plane doesn't believe that Joker's plan will work, based on the fact that's he's tried to destroy Gotham dozens of times and has always been defeated by Batman, Joker informs him that his plan will work this time as he's had his minions take over the Gotham Nuclear Plant, plant a bomb powerful enough to destroy the city on to it and had Egghead pelt the Bat-signal with eggs to prevent Batman from arriving.
With Joker and his minions threatening to destroy Gotham and Batman not being able to help, Commissioner Gordon and the GCPD are forced to surrender the Mayor of Gotham to Joker and his henchmen, however, unknown to them, the Mayor was actually Batman in disguise. As Batman begins to effortlessly pummel his minions, Joker begins to become frustrated as they're making him look bad in front of him. As Joker's bomb begins to reach the end of it's countdown, his minions abandon the plant and Joker uses his balloons to try and evade Batman, however, he grabs Joker with his grappling hook and uses another hook to hold them in place. When Joker refers to himself as his greatest enemy, Batman shuts Joker down and tells him that he means absolutely nothing to him and that Superman is a much better arch-nemesis, despite him not even being a villain. Batman eventually lets the heartbroken Joker go in order to defuse the bomb.
While in his lair, a frustrated Joker laments to Harley Quinn about how Batman doesn't respect him as a villain and how incompetent his minions are, all while watching an interview between Superman and Lois Lane. When Superman talks about how he was forced to imprison General Zod inside the Phantom Zone, he also mentions how the Zone has some of the evilest villains of all time housed inside it.
During Commissioner Gordon's retirement party, Joker and his minions arrive and Joker orders Mr. Freeze and Clayface to bring him the new commissioner, Barbara Gordon, all while Harley Quinn changes into her civilian identity of Harleen Quinzel. However, Barbara fights off Joker's minions and confronts him at the same time as Batman and Joker reveals that he actually wants to be arrested and go to jail for his crimes, to the surprise of everyone, including his minions. While Batman is in complete denial of Joker's willingness to be imprisoned, he insists he is serious and traps all of his minions inside a giant present box.
With Joker and all of the other villains in jail, Batman sinks into a depression and spies on him and the other inmates, believing them to be up to something. At this point, Joker has Harleen drive up to Arkham Asylum with a van for "Phantom Zone Laundry" and Batman is inspired to put Joker in the Phantom Zone to keep him from committing crimes for good.
After stealing the Phantom Zone projector from the Fortress of Solitude, Batman and his adopted son Dick Grayson try to sneak it into Arkham, but are caught and are forced to fight through Arkham's security in order to get to Joker's cell. Batman confronts Joker and sends him to the Phantom Zone, but is arrested and locked in a cell shortly afterward.
Joker then happily descends into the Phantom Zone and, after being scanned for how evil he is by the Zone's gatekeeper Phyllis, Joker meets the other prisoners of the Phantom Zone: Voldemort, Sauron, King Kong, The Wicked Witch of the West and her Flying Monkeys, The Daleks, the Velociraptors and Tyrannosaurus Rex from Jurassic Park, Agent Smith, Kraken, Gill-man, Dracula, Medusa, Jaws, the Skeletons from Jason and the Argonauts and the Gremlins. Upon his arrival, the villains try to kill Joker, but he tells them all that he can get them out of the Phantom Zone and they agree to work for him in exchange. At that moment, Harley Quinn steals the Phantom Zone projector and sets it to release all of the villains entrapped in the zone. Upon doing this, Joker, as a giant face over the city, tells Gotham that he is going to take over the city with the help of real villains before unleashing them on the city.
Joker then has Sauron tell him the location of the Batcave and, after failing to realize that Bruce Wayne and Batman are the same person, he trashes the cave and converts Wayne Island into an amusement park. After Batman, Dick, Barbara Gordon and Alfred evade his attacks, destroy Sauron and crash land on Joker Island, Batman has the Scutler take his friends away from the island so he can stop Joker without endangering them. After being caught by Joker and his minions, Joker tries to get him to admit that he is his most hated enemy, but Batman refuses (When Joker says "I hate you", Batman heartlessly responds "Me too"). Finally exasperated, Joker tells Batman that his only real greatest enemy is himself and banished Batman to the Phantom Zone. Joker and his minions then leave the Island and prepare to use Joker's bomb to destroy the city.
Upon being released with the promise that he will return all the escaped criminals, Batman teams up with Dick, Barbara, and Alfred, along with all the villains who escaped from Arkham to take down Joker and his minions. After the Phantom Zone villains are re-imprisoned and the city is blown up by the bomb, Batman convinces Joker to help him save the city by admitting that he truly is his greatest enemy. Upon saving the city, Joker and Batman's villains walk away as Batman gives them a 30-minute head start.
The Joker is extremely boastful, destructive, violent, traitorous, manipulative, sometimes sarcastic, and arrogant. He despises his acolytes for their incompetence against Batman. He also showed that he was very wounded by Batman when he told him that in his eyes he was nothing. But near the end of the movie, Batman says that he's the reason he still fights crime in the city.
Unlike most versions, this Joker takes his desire to make Batman hate him to new levels. Unlike most of his other incarnations whom care as much about causing chaos, this Joker focuses on making Batman consider him a true foe to the point where he becomes angry when Bruce refuses. This trait, however, does make him somewhat sympathetic given how Batman disregards him and how it genuinely hurts Joker.
When Batman admitted to Jokers he is Batman’s greatest enemy, Joker teamed up with Batman and helped him save Gotham City. He was even happy when Batman didn’t have to stay in the Phantom Zone and was on much more friendly terms with Batman afterwards. Joker wasn’t abusive to Harley Quinn and treated her like an actual girlfriend as well.
You should be terrified. (Bill: Why?) Because I will be taking over the city. What? (Bill: Batman will stop you. He always stops you.) No he doesn't. (Bill: What about that time with the two boats?) This is better that the two boats. Well, TONIGHT, is gonna be different. Tonight is my greatest plan yet. And trust me, Batman's never gonna see it coming.
~ Joker bragging about his plan.
Batman ? What are you doing? You're completely outnumbered here! Are you nuts? (Batman: You want to get nuts? Come on! Let's get nuts! Cause I wrote a song about how I'm gonna kick all your butts.) Stop him before he starts singing.
~ Joker when Batman literally shows up despite being alone.
(Batman: Looks like your plan failed.) Well, it's only a matter of time before I take over Gotham City. (Batman: When does that ever happen? Computer.) (Computer: Calculating. Never.) (Batman: You know why? Because, I'm always a step ahead of you.) And I always get away. (Batman: Not this time. Cause this time... I've got you.) Oh, yeah? Well, there's only one problem. Who's gonna defuse the bomb? It's gotta be one or the other, Batman. Save the city, or catch your greatest enemy. You can't do both. (Batman: I'm sorry. What did you just say?) You can't do both, I said. (Batman: No, I mean the other thing.) Save the city, or catch your greatest enemy. (Batman: You think you're greatest enemy?) Yes! You're obsessed with me. (Batman: No, I'm not.) Yes, you are. (Batman: No, I'm not.) Yes, you are! Who else drives to one up in the way that I do? (Batman: Bane.) No, he doesn't. (Batman: Superman.) Superman's not a bad guy. (Batman: Then I'd say I don't currently have a bad guy, I am fighting a few different people.) What? (Batman: I like to fight around.) Okay, look. I am fine with you fighting other people if you want to do that. But what we have is special. So, when people ask you, "Who's your number one bad guy?" You say...(Batman: Superman.) Are you seriously saying that there is nothing, NOTHING special about our relationship?! (Batman: Whoa. Let me tell you something, J-Bird. Batman doesn't do ships.) What? (Batman: As in, "Relationships", there is no "us." Batman and Joker are not a thing. I don't need you. I don't need anyone. You mean nothing to me. No one does.)
~ Joker gets heartbroken when he learns that Batman never considered him his greatest enemy.
Oh, my gosh! (Phyllis: Sorry. I always do that.) How about a warning next time? (Phyllis: You're so right, and I am so wrong. Welcome to the Phantom Zone, bad guy.) Yeah, "bad guy. (Phyllis: My name is Phyllis.) Oh, that was my grandma's name. (Phyllis: Now hold still while I scan you. Scanning for badness. Trying to access whether you are bad. Ugh! Your whole thing screams "bad guy.") Oh, yeah. I'm a really bad person. (Phyllis: But with vulnerabilities.) Who, me? No way. So, where do you keep all the other bad people in this place?
~ Joker meets Phylis in Phantom Zone.
Whoa! Hi there, guys. Lovely to meet you all. I'm the... Oh, fist bump? There we... Handshake? It doesn't matter. I'm the Joker. (Sauron: Take a look at the new guy.) (Kraken: Guess they'll just let anybody in here.) Oh, no, no, no. I'm very bad, too. They just showed a video montage... (Sea Monster: Boring!) What? (Sea Monster: You're boring.) (Bruce Shark: He looks delicious.) (Rexy: Let's eat this guy.) Stop with the violence for just a second! What if I told you I could get you outta here? (King Kong: I'm sorry, what'd you just say?) That's right. I'm so bad, I got myself thrown into this heck-hole on purpose! (Kraken: I'm listening.) (Dracula: Count me interested.) Look, everyone here knows what it's like to be hurt by a hero, don't they? We've all been taken for granted, right?(King Kong: Yeah, bro.) (Wicked Witch: I'm relating!) Well, that's why I came to this space prison. To recruit the universe's greatest... (Voldemort: We'll do it!) I'm sorry? (Voldemort: You were going to say something about recruiting the universe's greatest villains to conquer a superhero. Am I right?) Uh, yeah. (Voldermort: Well, we're in!) Yay! Really? Because I brought a PowerPoint... (Sea Monster: Still boring!) (Flying Monkey: Yeah. Just get on with it.) (Kraken: You want us to humiliate him?) I certainly do. Yes. (Medusa: You want us to make him grovel at your feet?) I would like to see that very much! (Agent Smith: You want us to smite him?) Well, yeah, yeah, yeah. (Sauron: You want us to make the rivers of Gotham City run red with his blood?) Oh, that's... (Sauron: Oh, no blood? How do you feel about lava?) Yes! Lava. (Agent Smith: Done.) All Villains: Yay! (King Kong: I can't wait to crush buildings.) (Velocirator: Excuse me. Hello? Over here. I don't want to be a downer, but how exactly are we going to get outta this place?) Oh, leave that to me.
~ Joker rally all the villains of the Phantom Zone to his cause.
Joker's deranged grin
Joker heartbroken after Batman tells him he is nothing.
Joker's evil grin.
Joker after temporarily teaming up with Batman.
The Joker is surprised to see Batman making him an offer of redemption.
Everyone thinks the Joker is the deuteragonist because he redeemed himself at the end of the film.
This is, by far, one of the few versions of the Joker to not be depicted as horrible and completely monstrous without redeeming qualities but more as a lighthearted troublemaker (unsurprisingly, since the filmmakers intended to make the movie a family film). He is insecure about his rivalry with Batman, treats Harley Quinn like his actual girlfriend instead of abusing her and helps Batman save Gotham City at the end.
Joker is surprisingly similar to Batman: They are both amazingly proud and jerky. They are also a sensitive side as when Batman becomes depressive since the city no longer considers him a Hero, Joker when Batman tells him that it is absolutely nothing for him, leaving him emotionally annihilated. Both of them become nicer at the end with Batman finally accepting Robin, Barbara and Alfred as his partners and admitting to Joker he is Batman’s greatest enemy while Joker helps Batman save Gotham City. Joker was even happy when Batman becomes nice enough to not have to go back to the Phantom Zone.
Not counting his comic counterpart's numerous non-canon team-ups with villains from the Marvel universe (such as Red Skull and Carnage), this version of the Joker is the only one to have teamed up with villains from outside the DC universe.
This version of the Joker is the only version of the Joker to have assembled such a large army of supervillains. It should be noted that, while it has many of Batman's more traditional foes, such as the Penguin, the Riddler, Bane, Catwoman, Killer Croc, Scarecrow, Posion Ivy, Two Face and the previously mentioned Mr. Freeze, Clayface and Harley Quinn, Joker's army is mostly composed of many of Batman's lesser known and ultimately terrible villains, such as Calendar Man, Condiment King, Signalman, Kite Man, Killer Moth, Orca, Polka Dot Man, Crazy Quilt, The Eraser, King Tut, Magpie, Catman, Zebra-Man, the Kabuki Twins, Hawkman foe Gentleman Ghost, Flash foe Captain Boomerang and Green Arrow foe Clock King.
His voice actor, Zach Galifianakis previously worked with Batman's voice actor Will Arnett in the 2009 live-action Disney film G-FORCE.