Blue Kryptonite was a variant of Kryptonite which only affected Bizarros. In Pre-Crisis continuity, Superman once used a Bizarro Duplicator Ray on a piece of Green Kryptonite, transforming it into Blue Kryptonite. He then used the altered Blue Kryptonite to halt an army of advancing Bizarros. Blue Kryptonite only affects Bizarros and is harmless to humans and Kryptonians.
- In Post-Crisis continuity, like Bizarro himself, Blue Kryptonite is opposite to the more common green variety--it will make Kryptonian-based Bizarros (see Batzarro) highly intelligent (up to 12th level intellect), a process that seems to scare Bizarro and his ilk.
- Post-Infinite Crisis, Blue Kryptonite appears to have reverted back to its original form as it has been seen (as of Action Comics Annual #10) to affect Bizarro in a painful manner reminiscent of the effect that Green Kryptonite has on Superman.
- Blue Kryptonite was introduced in the seventh season of Smallville. It strips or rather suppresses Clark's powers, at least for a time, making it similar to the Post-Crisis version of Gold Kryptonite. During this time, Clark was also immune to the effects of Green Kryptonite. It was forged into Jor-El's victory ring which was presented to him when he first became a member of the Kryptonian Council. Clark's resurrected mother Lara Lor-Van gave him the victory ring, telling Clark that it was a Kryptonian tradition to pass the victory ring onto the firstborn son when he came of age. The ring had been a trap set by Zor-El, to strip Clark of his powers. Since on their own homeworld, Kryptonians have no powers, Lara had no way of knowing that Blue Kryptonite would strip Clark of his abilities. In the Season 7 episode "Persona", Clark used Blue Kryptonite to overload and kill Bizarro
- In the The New 52, an enemy apart of the Anti-Superman Army dubbed the Blue K-Man states that his Kryptonite radiation wavelength is cancerous to the soul. Xa-Du The Phantom King, recoiled out of fear while in this Kryptonite Man's presence due to being an ethereal being of the phantom zone. Stating that Blue Kryptonite radiation causes spiritual death, making it the most lethal form of Kryptonite to date.
- In the Super Friends episode "Terror from the Phantom Zone", Blue Kryptonite was used by Superman to reverse the effects of an exposure to Red Kryptonite that caused him to rapidly age.
- In the Super Friends episode Bazarowurld Superman claims that when the radiation of Red Kryptonite passes through his blue suit it turns into Blue Kryptonite.
- In Justice League: Crisis on Two Earths, Blue Kryptonite has the same effect on Ultraman as Green Kryptonite on Superman and was used by the Crime Syndicate Earth's Luthor to defeat Ultraman.
- In the Supergirl live-action series, blue kryptonite was synthesized by the DEO in order to take down Bizarro after green kryptonite proved inadequate for the task. It was stated to be opposite of regular kryptonite with a reversed ionic charge.