This study investigates whether the timing of sponsorship disclosure affects viewers’ processing of sponsored content, and whether a disclosure influences the persuasive effect of the sponsored content. A model is proposed in which sponsorship disclosure enhances the recognition of sponsored television content as advertising, which leads to critical processing of the sponsored content. Ultimately, this negatively affects the attitude toward the brand in the sponsored content. This model was supported, but only when the disclosure was displayed prior to or concurrent with the sponsored content. These effects were not found for a sponsorship disclosure shown at the end of the program after the sponsored content. Theoretically, the findings emphasize the importance of disclosure timing. A disclosure displayed prior to or concurrent with the sponsored content, primes the sponsored content and provides sufficient processing time, so viewers recognize the content as advertising and can process it critically. In addition, the findings show that persuasion knowledge and critical processing are important underlying mechanisms for the effect of sponsorship disclosure on brand attitude. Regarding the practical implications for legislators and advertisers, this research demonstrates that sponsorship disclosure can make viewers aware of the sponsored content in television programs. Furthermore, this changes the processing of sponsored content and can also ultimately lead to resistance against persuasion.