In boxing, a knockout (KO) is when a boxer stays down for a count of 10 from the referee, at which point the boxer loses the match to his opponent. If the boxer manages to get up, he can continue the fight until he gets knocked down (KD'd) again. In Punch-Out!!, though, if the boxer falls down three times within one round, it will count as a technical knockout, and the boxer forfeits the match to his opponent. There are currently 25 known One-Hit Knockouts in this game.
Like all of the challengers in Punch Out!!, the player (Little Mac) can be KO'd and TKO'd. As Mac is smaller and less resilient to punches and knockdowns, he will be KO'd after 3 or 4 total knock downs if the player does not perform a KO Recovery which allows 1 more KO. When the player is KD'd they will fall to the mat and the referee will begin counting to 10. How quickly the player gets up after a KD will determine how much health they recover when they get up. This will decrease after each KD. To regain the maximum amount of health, the player has to get up slowly, but not too slowly. If the player recovers at a slow and steady pace, usually ending at the count of 4 or 5, they will regain much more health than if they mashed the buttons or waited until the count of 9.