While all vulnerable adolescents are more at risk online than their non-vulnerable peers, those with special educational needs (SEN) require targeted and specialised support. Although they are not a homogenous group, SEN adolescents commonly experience social isolation and a lack of connection or meaningful relationships with peers in their offline lives. Many perceive the internet as a route to alternative means of communicating and interacting with others. Accessibility tools enable autonomous access to the online world, which offers support groups, new friends, entertainment, and connections. This can lead to both potential online relationship-risk encounters and positive experiences. With the attraction of online environments comes the need for digital skills and awarness of possible online risks, yet for adolescents with SEN, their difficulties dictate a need for more than rules, controls, and digital skills. In this study, 4894 adolescents aged 13 to 17, of whom 1207 had SEN, completed the Cybersurvey 2019, an online questionnaire about their digital life. Adolescents were asked about the benefits of using the internet, their online safety support, offline social support, and any online relationship-risk encounters. All participants were recruited through their schools. Descriptive statistics and multiple analysis of variance tests showed that, compared with their peers, adolescents with SEN experienced significantly more social isolation and less parental online safety support. They were also more likely to use the internet for positive purposes, such as socialising and coping. Overall, adolescents with SEN encountered more online relationship risks than their non-SEN peers, with older teens more likely to encounter such risks than younger peers, regardless of their SEN status. Multiple analysis of variance tests also identified that boys perceive internet use as positive to a greater extent than girls, suggesting a gender difference in experiences of the digital environment. A multiple linear hierarchical regression revealed that SEN status, age, social isolation, poor parental online safety support, and greater perceived positive internet use, all significantly predicted online relationship-risk encounters. This article discusses important implications and recommendations for policy and practice related to SEN and online safety and highlights areas for future research to consider.