Background Sexual health service engagement is important for the healthy sexual development of young people. Further, as later adolescence and early adulthood are critical periods for relationship development, sexual health needs may vary across this period and be associated with relationship status. Methods A total of 468 participants, aged 16-25years (mean age: 19.7years) and living in the United Kingdom, completed an anonymous, online survey about their sexual health service use. To explore how relationship status is associated with engagement for five different sexual health services, we conducted chi-squared and multivariable logistic regression analyses. Results In general, engagement with sexual health services was low: 28.2% reported accessing free condoms, 21.4% reported STI testing, and 9.4% had used relationship advice services. Among women only, 57.2% had accessed services to start the pill and 19.6% had done so for pregnancy testing. Among all participants, those in relationships were more likely to have accessed sexual health services for free condoms (aOR: 1.71, 95% CI: 1.13, 2.59). Among female participants, those in relationships were more likely to have accessed sexual health services to start the pill (aOR: 2.21, 95% CI: 1.45, 3.36) and for pregnancy testing (aOR: 3.86, 95% CI: 2.20, 6.78). There were no differences by relationship status for accessing sexual health services for STI testing or relationship advice. Conclusions Health care providers and relationship and sexual education providers should encourage all young people to engage with sexual health services, while also recognising that sexual health needs are likely to vary depending on relationship status.