The Joker first appears at the beginning of The LEGO Batman Movie having gathered all of Batman's enemies in an attempt to seize control of the city by blowing up the power plant. This scheme soon fails as Batman arrives and beats all of the villains forcing them into a retreat and leaving Joker to fight Batman himself the in ensuing battle Joker attempts to escape but Batman catches him with a grappling hook and they both have an emotionally damaging argument on why the Joker isn't Batman's greatest enemy leaving Joker heartbroken while Batman defuses the bomb. Joker feeling down after the battle sees a news report on Superman who had recently banished General Zod to the Phantom Zone amongst some of the most evil villains in pop culture history to which Joker soon finds inspiration for a bold new plan to conquer Gotham. At Commissioner Gordon's retirement party Joker and all his villainous allies attack the celebration but before any actual fight can break out Joker and all the villains (except Harley Quinn) apparently surrender to the new Commissioner Barbara Gordon and is taken to Arkham Asylum, leaving the city crime-free and leaving Batman with a loss of purpose, though being suspicious of the Joker's sudden surrender he spies on the prison when Harley is disguise as a nurse shows up in a truck with the logo "Phantom's Own Laundry" to which Batman soon gets the idea to put Joker in the Phantom Zone. After obtaining the Phantom Zone projector from Superman Batman breaks into Arkham and uses the projector on Joker sending him where he supposedly can't harm Gotham anymore. But in truth, this was exactly what Joker wanted and he soon met with some of the most famous villains in pop culture and successfully convinces them to aid him in defeating Batman and destroying Gotham city. Harley in her nurse disguise sneaks into Arkham and steals the Phantom projector and releases all the villains and they rampage through the city, before heading to the Batcave and seizing control of all Batman's technology and weapons and turning Wayne Manor into their headquarters as well as a makeshift amusement park. Batman soon makes his way into Joker's trap and Joker then begins playing mind games on the dark knight mocking him for pushing everyone away leaving him all alone, upon breaking Batman's spirit Joker sends Batman to the Phantom Zone and orders his army of villains to gather up explosives so he could finally destroy Gotham city. Batman soon escapes the phantom zone and gathers his new bat family as well as his B - Z list villains to stop the Joker and his army, even after an awesome conflict and all of the Joker's new allies sent back to the Phantom Zone they are unable to stop Joker's bomb from detonating and the explosion soon destabilizes the city's tectonic plates and opens up a whole in the earth and down below revealing the bottomless pit from The LEGO Movie in which Emmet fell into. Batman soon sends a message to all citizens to unite into human ladders and try to pull the city back together but Batman's human ladder is too short and Joker then laughs and taunts Batman, but Batman then convinces the Joker to take his hand and help in saving the city by saying that Joker is Batman's greatest enemy and if the city is destroyed Joker wouldn't be able to fight Batman anymore. After the city is saved Batman gives the Joker a head start before Batman gives chase thus everything is as it should be between the two arch-enemies never-ending struggle. During the end credits the bat family joins the Joker and all the B - Z list bad guys in a final ending musical number.
He is voiced by Zach Galifianakis in the movie. In the game, he is voiced by André Sogliuzzo.