A unanimous decision is a decision or judgment that is formed or supported by everyone in a group. In the context of full-contact combat sports such as boxing, kickboxing, Muay Thai, mixed martial arts, and other sports involving striking and submission, a unanimous decision is a winning criterion in which all three judges agree on which fighter won the match. In boxing, each of the three judges keeps score (round by round) of which fighter they feel is winning based on landed blows to the head or the body. In MMA, judges look for different criteria such as kicks, take downs, punches, knees, elbows, cage control, submission attempts, and aggression. A decision is not required to be unanimous for a boxer or mixed martial artist to be given a victory.

It is important to note that a unanimous decision should not be confused with a majority decision or split decision. In a majority decision, two of the three judges agree on the winner, while in a split decision, two of the three judges agree on the winner, but the third judge scores the fight as a draw.

In other contexts, a unanimous decision refers to a group of people who all agree about one particular matter or vote the same way. For example, a school board may be unanimous in its support of a decision. Unlike a jury verdict, an appellate court decision does not have to be unanimous, and a majority decides the case.