Voice commerce allows customers to carry out sales dialogues with voice assistants (VAs) through natural spoken language. However, its adoption remains limited. To help determine how to overcome existing barriers to adoption, we conducted a series of three empirical pre-studies and a laboratory experiment (N = 323) investigating the role of VAs’ humanness in interactions with customers; research has reached no consensus on this matter. Our results reveal that humanizing VAs increases customers’ perceptions of social presence and parasocial interaction, thereby enhancing perceived relationship quality and ultimately leading to increased intentions to shop using the VA. Although, we also find a negative direct effect of humanization on parasocial interaction, it is offset by the larger positive indirect effect via social presence. This may provide one explanation for the inconsistencies in the literature. For practitioners, our findings highlight the importance of careful design in humanizing VAs to increase voice commerce adoption.