Scholars, educators, and policymakers have expressed concerns about the sexualization of youth in popular social media platforms. Yet little is known about the prevalence of sexualized content on social media and who is most likely to post it. This study considers adolescents in three European countries (i.e., 115 Belgium, 134 France, and 118 Slovenia; Mage = 16.40, SD = 1.60, 62.10% girls) who donated their most recent posts, profile picture, and/or stories from TikTok, Instagram, and/or Snapchat, which were coded for sexualization. The results showed that almost four in ten adolescents had recently posted sexualized visual content on social media, particularly with a sexualized facial expression. No significant within-person differences emerged in the amount of sexualization depending on the platform nor content type. Sexualized self-presentations were not related to the country origin of the user or negative body image of the user. However, girls showed three times as much sexualization in their social media data compared to boys. Finally, users did not perceive that their sexualization content received more positive likes or positive comments than usual. These results broaden our understanding of the prevalence and content of sexualized self-presentations by youth on social media.