With the increased use of online communication in our everyday lives, there is a growing need to understand social influence in such settings. The current research posits that online social norms can influence readers‟ anti-social and pro-social behaviours online, specifically individual expressions of prejudice. Participants read an online article proposing an increase to international student scholarship funding, then were randomly placed in one of two normative conditions where they read Anti-Prejudiced or Pro-Prejudiced comments allegedly placed by other users. Participants then left their own comments before completing a self-report prejudice questionnaire and an implicit association test (IAT). Social norms created by the fictitious comments influenced respondents to comment with more or less bigoted sentiments aligned with the fictitious social norm. Participants reading prejudiced online comments showed increased implicit and explicit prejudice, while those reading anti-prejudiced online comments showed the reverse. Participants‟ internal and external motivations to control prejudice were also measured and hypothesised to moderate the effects of social norms on bias expressions. However, this hypothesis was unsupported with participants‟ internal and external motivations to control prejudice inconsistently moderating the effects of the social norm on their prejudice expressions. These findings suggest possible avenues for social change in online environments, and criteria to help establish more positive online social norms.