The disclosed computer-implemented method for authenticating a multimedia stream may include generating a metadata transcript based on at least a portion of a multimedia stream and digitally signing the metadata transcript. The method may also include transmitting both the digitally signed metadata transcript and the multimedia stream to a recipient device to enable the recipient device to authenticate the multimedia stream. The recipient device may authenticate the multimedia stream based on a comparison of the digitally signed metadata transcript with an observed metadata transcript. The observed metadata transcript may be locally generated by the recipient device based on the multimedia stream. Various other methods, systems, and computer-readable media are also disclosed.