Previous research has acknowledged the role of pro-market reforms, yet there has been limited discussion regarding how antitrust legislation, a specific type of increasingly prevalent market-oriented institution in recent decades, can influence SME internationalization. Drawing on the attention-based view and institution-based view, this study argues that antitrust legislation in emerging economies leads SMEs to focus their product market attention and efforts on domestic markets, thereby reducing their inclination toward internationalization. As predicted, our analysis of a sample of 26,412 firms from emerging countries indicates a significantly negative impact of antitrust legislation on the product market internationalization of SMEs. The results also reveal that both group affiliation and domestic private ownership negatively moderate the relationship between antitrust legislation and the product market internationalization of SMEs.