Mr. Freeze is a antagonist in the animated TV series Young Justice, first appearing in the pilot episode Independence Day.
In Gotham City, Freeze targes families picknicking in a park. He freezes them with his ice ray, remarking that while these families are enjoying family time, his family has other plans. He then freezes one family, using the ice as a ramp to slide down into the park. When a batarang hits the ground next to him he turns, expecting Batman. Instead Robin jumps onto him, smashing him to the ground and cracking his visor. Annoyed that he has to face Robin instead of Batman he gets back up, stating that he is underwhelmed. He is then attacked from behind by Batman who takes him down and breaks his helmet completely. Interestingly, the day he attacks all other members of the Justice League face ice-based villains as well.
In this episode it is revealed that after his defeat, Freeze had been sent to Arkham Asylum but petitioned to be declared legally sane. He was thus sent to Belle Reve Prison. As the other three ice villains (Captain Cold, Icicle Jr., Killer Frost) were also sent to Belle Reve, the Justice League became suspicious and decided to investigate. Superboy and Miss Martian are sent to the prison, disguised as inmates.
Arriving at the prison, the frost villains and the heroes are greeted by warden Amanda Waller. She introduces himself and accustoms the prisoners to the collars they are wearing around their neck, revealing that the collars inhibit the wearer's powers and can also be used to deploy electricity charges. In prison, Freeze immediately teams up with the higher ranking prisoners, including Icicle sr. and Mammoth. It is revealed that the ice villains deliberately let themselves get caught in order for Icicle sr. to have enough power to cause a riot and to break out all prisoners inside Belle Reve. With help from a bought security guard, Freeze is able to get his freeze gun.
As part of their plan, Freeze seemingly attacks Icicle to usurp his position as gang leader. Security guards bring him to Waller where he uses one of his smuggled devices to freeze the man guarding him. When Waller locks down the facility and attempts to shoot him, he freezes her gun and her entire arm. Freeze gains control over the collars and is able to deactivate them. The prisoners are now able to use their full strength and a riot starts. After the prison is secured, Freeze, Icicle and Captain Cold use their freeze rays on a wall, hoping to shockfrost it enough in order for the super-strong prisoners to break it.
When Superboy manages to activate the shock-collars again, the only ones not affected are Freeze and Icicle sr. as well as Mammoth, who destroyed their collars before. Freeze returns to the control room, realising that the collars had been turned on again. He, Mammoth and another strong villain confront Icicle jr. (who has no idea that Superboy is playing him) and Superboy. Superboy convinces Icicle that Freeze is lying to him in order to usurp his position as Icicle sr.'s right-hand man and Icicle attacks Freeze while Superboy fights the strong ones. As each of the two is outmatched they decide to swap their opponents. Superboy easily knocks down Freeze, shattering his suit in the process. As Freeze can only survive in temperatures below zero, he shoots his freeze ray at himself - freezing his own head but ensuring his survival.
Mr. Freeze is one of the criminals suspected by the Justice League to be responsible for sending five flying ice fortresses causing severe snowfall over all of America. However, when Batman shares this theory with Belle Reve warden Hugo Strange, Strange reveals that Freeze had been in his cell the entire time. In truth, the ice fortresses were part of a scheme of Count Vertigo, who tried to usurp the throne of his home country.