“I'm out” is the phrase Dragons' Den investors use when they decide not to invest.
During a pitch, each dragon can question the entrepreneur and then decide whether to make an offer. When an investor says “I'm out”, that person withdraws from consideration and will not participate in the deal being discussed. The short declaration has become one of the programme's most recognisable expressions.
The phrase does not necessarily mean that every dragon has rejected the entrepreneur. Other investors may still remain interested, negotiate different terms or make competing offers. A pitch can therefore continue after one dragon has left the discussion.
Viewers sometimes confuse “I'm out” with the moment a deal is completed. In fact, it signals the opposite for that particular investor: the dragon has chosen not to proceed. The wording is also part of the show's familiar presentation style rather than a formal legal term.