The smart speaker is currently one of the fastest-growing consumer technologies. As a result, more and more people are buying products through smart speakers. However, because voice commerce advertisements are not yet active, little is known about the effectiveness of smart speaker advertisements. This study assessed advertisement effectiveness using several distinctive features of the smart speaker: interactivity, contextually relevant advertisements, and voice changes. Study 1 illustrates that when users interact with an advertisement from the speaker, the effects of the advertisements are more significant than the effects of one-way advertisements, especially in the case of low involvement products. Study 2 further illustrated that contextually relevant advertisements increase the advertisement effectiveness from the smart speaker, while voice dissimilarity moderates the relationship between the contextual relevance and the effectiveness. These findings provide future directions for producing the new forms of advertisements and verifying advertisement effectiveness in the smart speaker environment.