In recent years, social media has been widely used as a tool for feminist social movements, addressing social problems such as sexual assault traumatization. This research aims at understanding how social media users utilized Twitter to describe traumatic sexual assault experiences and reasons victims chose not to disclose their experiences (Study 1), and how users became a part of the digital activism (i.e., social media movement against sexual assault) to increase social actions (Study 2). Tweets using the hashtag #WhyIDidntReport and #MeToo were extracted. Thematic analyses were used to analyze tweets across the two studies. Results from Study 1 revealed that social media victims who self‐disclosed their victimization stories often reported having serious psychological impacts, a sense of helplessness, and issues with the police. Study 2 further uncovered that social media users engaged in hashtag activism through discussing views on relevant political and social issues, sharing resources to help sexual assault victims, and promoting social actions (e.g., protests, voting).