A multimedia content conversion apparatus and method, and a multimedia content distribution system are provided. The apparatus includes a storage unit storing original data received from a multimedia content provider, an authentication unit determining whether a viewer is authorized with respect to the original data stored in the storage unit, a decryptor decrypting the original data if it is determined by the authentication unit that the viewer is authorized, and a data combiner combining the original data and the data decrypted by the decryptor. Accordingly, even if several TVs are installed in a home, a viewer can view desired multimedia content through all of the TVs with only one content conversion apparatus. Even when the viewer watches a TV in which the content conversion apparatus is not included, the viewer can view desired multimedia content by changing a channel of a TV which includes the content conversion apparatus. Since the content conversion apparatus provides content of various image standards, the viewer can view desired content regardless of a type of TV being used.