Abstract Introduction The South African public health system plays an important role in the delivery of HIV testing and treatment services. The health system is also an important conduit for targeted behaviour change communication with the expectation that clients who undergo counselling from health personnel, adopt safer sexual practices. Literature remains mixed on the impact these HIV services have on risky sexual behaviour. This analysis examines the sexual behaviour of clients following the utilisation of HIV testing and treatment services in Kwazulu-Natal, South Africa. Methods Data were used from two consecutive cross-sectional household surveys undertaken from June 2014 to June 2015 (2014/2015 survey) and from July 2015 to June 2016 (2015/2016 survey) in the uMgungundlovu District of KwaZulu-Natal, South Africa. Collectively, 20,048 randomly selected individuals aged 15 to 49 years old were interviewed across the two surveys. Utilisation of HIV testing and treatment services were used as independent variables and three sexual risk behaviours were used as dependent variables. Multiple regression models assessed the impact HIV testing and treatment services had on sexual risk behaviour while controlling for socio-demographic characteristics. Results Having tested for HIV had no association with any of the three sexual risk behaviours. However, receiving an HIV positive diagnosis reduced the likelihood of using condoms inconsistently with the respondents’ most recent partner (AOR: 0.64; 95% CI 0.54–0.77). Antiretroviral use was negatively associated with inconsistent condom use (AOR: 0.45; 95% CI 0.35–0.58) and number of sexual partners in the previous year (AOR: 0.61; 95% CI 0.46–0.81). Conclusions Results indicate that HIV testing and treatment services and the assumed exposure of clients to behaviour change communication, had a limited effect in reducing risky sexual behaviour. Data suggests that the engagement between health personnel and individuals accessing HIV testing and treatment services does not necessarily translate into the adoption of safer sexual practices, with the exception of individuals testing positive for HIV and those on ARV treatment, who had adopted safer sexual practices.