© 2016 The Author(s)Disclosure of HIV status to family, friends, and a stable partner may be linked to improved health outcomes for people living with HIV. This study assessed whether non-disclosure is associated with psychological symptoms, non-adherence to antiretroviral therapy (ART), and viral load (VL) non-suppression. A total of 3258 HIV-diagnosed individuals in the UK completed the confidential ASTRA study questionnaire (2011–2012). Participants reported whether they told anyone they had HIV; to which confidant(s) (friends, family, work colleagues, stable partner) and to what extent (none, some, most/all). The prevalence and factors associated with non-disclosure were assessed. Associations between non-disclosure and the following factors were established using modified Poisson regression with adjustment for socio-demographic factors (gender, age group, ethnicity), HIV-related factors (time since HIV diagnosis, ART status), and clinic: low social support (score ≤ 12 on modified Duke-UNC FSSQ); depression and anxiety symptoms (≥10 on PHQ-9 and GAD-7 respectively); self-reported ART non-adherence in past 2 weeks/3 months; VL non-suppression (clinic-recorded VL > 50 copies/mL among those who started ART ≥ 6 months ago). Among 3233 participants with disclosure data, the prevalence of non-disclosure to anyone was 16.6 % (n/N = 61/367) among heterosexual men, 15.7 % (98/626) among women, and 5.0 % (113/2240) among MSM. MSM were more likely to disclose to some/all friends compared to family (85.8 vs. 59.9 %) while heterosexuals were less likely to disclose to friends than family (44.1 vs. 61.1 % for men, 57.5 vs. 67.1 % for women). Among 1,631 participants with a stable partner, non-disclosure to a stable partner was 4.9 % for MSM, 10.9 % for heterosexual men, and 13.0 % for women. In adjusted analyses, older age (≥60 years), non-white ethnicity, more recent HIV diagnosis, and not having a stable partner were significantly associated with overall non-disclosure for MSM and heterosexual individuals. The prevalence of low social support was 14.4 %, of depression and anxiety symptoms 27.1 and 22.0 %, respectively, of ART non-adherence 31.8 %, and of viral load non-suppression on ART 9.8 %. There was no evidence that non-disclosure overall (versus disclosure to anyone) was associated with low social support, depression or anxiety symptoms, ART non-adherence or VL non-suppression among MSM or heterosexual individuals. However, compared to MSM who disclosed to ‘none’ or ‘some’ friends and family, MSM who disclosed to ‘most or all’ of their friends and family were more likely to have symptoms of depression (adjusted PR = 1.4, 95 % CI 1.2–1.7), anxiety (1.3, 1.1–1.6), and to report ART non-adherence (1.3, 1.1–1.5). In this large multicentre study of people living with HIV in the UK, non-disclosure was overall low, but higher for heterosexual individuals compared to MSM. Non-disclosure was not associated with higher prevalence of adverse health measures.