A mirror punishment is a penal form of poetic justice which reflects the nature or means of the crime in the means of punishment as a form of retributive justice — the practice of "repaying" a wrongdoer.

It can be an application of the lex talionis ("an eye for an eye"), but is not always proportional justice, as a similar method may be used to produce a worse or milder effect than the crime it punishes. The simplest method of mirror punishment is to enact the same action upon the criminal as the criminal perpetrated upon the victim. For example, one who steals from another has the same amount of money taken from them as they took from the other person; one who strikes another is struck in the same way; one who kills another is killed; and so on.

Often, however, a more esoteric method of mirror punishment is used, which implies punishing the part of the victim's body used to commit the crime. Extreme examples include the amputation of the hands of a thief, as still permitted by Sharia law, or during the Middle Ages in Europe; or disabling the foot or leg of a runaway slave. Other examples include the punishment of adulterous women by the insertion of irritating substances into their vagina, or the punishment of illegal homosexual intercourse by inserting harmful objects in the rectum. A less extreme example is the putting of soap into a child's mouth for using inappropriate language (called in American English "washing your mouth out with soap").

Another method is to mirror the physical method of the crime, e.g. executing a murderer with his own weapon, or in a more far-fetched example, boiling a counterfeiter alive (because bullion is boiled to be minted).