Social media have created new opportunities for Jewish community-building and education but are also used to disseminate antisemitic content. Individuals and political actors from various ideological backgrounds exploit these platforms, while algorithms amplify such hate speech. The Hamas terrorist attack in Israel on 7 October 2023 intensified this issue, leading to a surge in Israel-related antisemitism online. With this case study, we examine antisemitic discourse on the social media accounts of a Swedish Jewish youth organisation and its impact on the youths’ engagement with these platforms following the attack and ensuing conflict. We draw on data from interviews, a focus group, and posts (n = 115) and comments (n = 2,964) from X and Instagram. The findings reveal how rising antisemitism, particularly the “Israelisation of antisemitism”, affected young Jews, prompting self-censorship and withdrawal from unsafe online spaces. This study provides insights into the evolving nature of antisemitism in the digital age. It highlights the need for societal and technological responses to address the challenges posed by online hate speech.