Sexually transmitted infections (STIs) are frequently underdiagnosed, representing a serious public health concern, especially during adolescence and in more vulnerable communities. Aim: to describe the last ten years of emergency department (ED) visits for STIs among adolescents. Methods: a retrospective cross-sectional observation was carried out in the Piedmont region in Italy. Data were retrieved through the Italian National Information System database. ED visits related to specific ICD-9-CM codes carried out on 11 to 19-year-old youths between 2011 and 2020 were investigated. Age-specific, crude, and standardized rates and admission ratios, with 95% confidence intervals (CIs), were calculated to estimate the STI trend. Results: from a total of 1,219,075 ED visits, 339 were related to STIs, representing an increasing ratio of 28 per 100,000 visits, primarily in females. Most infections occurred in girls (83.5%) and among 17 to 19-year-olds (71.5%). A drop in both ED visits and STI cases was observed in 2020. Genital Herpes and Genital Warts were more frequent in girls while Gonorrhea was more frequent in boys. Conclusions: the increasing trend of ED visits for STIs, particularly in girls, represents an emerging relevant public health issue that needs to be urgently tackled.