Viral video advertising as a branded entertainment has shown its potential to overcome consumer skepticism by spreading the brand message through individuals’ social connection. Although brand placement prominence and brand disclosure may be critical factors that influence forwarding intention in the viral video ad context, less research has examined these relationship. To fill these gaps, this study aims 1) to examine the psychological mechanisms through which the brand placement prominence influences consumers’ forwarding intention of viral video advertising, and 2) to investigate the potential moderating role of brand disclosure timing. This study shows that the level of brand prominence in a viral video ad is an important factor influencing viewers’ forwarding intention sequentially mediated by persuasion knowledge, critical processing and enjoyment. The moderating role of brand disclosure timing investigated in the current study suggests that when the branded viral video has a high level of brand prominence, post brand disclosure leads to a higher forwarding intention compared to the prior brand disclosure.