Background Today’s young people have long been demanding a paradigm shift in the emotional and sexual education they receive. While for them, affective-sexual and gender diversity is already a reality, the sexual and reproductive health professionals they encounter lack sufficient training. The digital devices and affective-sexual education websites aimed at today’s young people must also be thoroughly evaluated. The website Sexe Joves is a website on sexuality by the Department of Health of the Government of Catalonia (Spain). It is designed for people aged 14 to 25 years. It currently needs to undergo a process of evaluation. Affective-sexual education aimed at young people must stem from their participation and the whole range of sexual and gender diversity in order to reach the entire population equally. Objective The aim of this study was to evaluate the website Sexe Joves as a source of affective-sexual health information, education, and communication for young people. It takes into account sex, gender identity, sexual orientation, socioeconomic status, and location within Catalonia (urban, semiurban, and rural areas). Methods This was an observational, descriptive, and cross-sectional study that forms part of a larger mixed methods study. An ad hoc questionnaire was used to collect data. In total, 1830 participants were included. The study was carried out simultaneously in all the territorial administrations of Catalonia. Results Almost 30% of the sample obtained were young people who experience affective-sexual and gender diversity. Of those surveyed, only 14.2% (n=260) said they were familiar with the website and of these, 6.5% said they used it (n=114). The website content rated most indispensable was on sexual abuse, harassment, and violence, followed by sexually transmitted infections; 70.5% (n=1200) reported that they visit pornographic websites. Conclusions The results of this study will contribute to the design of new strategies for the website Sexe Joves, a public health resource, in order to improve affective sexual education for young people. International Registered Report Identifier (IRRID) RR2-10.3390/ijerph192416586